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Cell Organelles. Class Presentation on Topic 2 4A– IB Biology HL . * RiBOSOMES *. Definition: Small spherical structures, consisting of two subunits. Key: ABC – from the HLB textbook ABC – from the AP Bio textbook

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Cell organelles

Cell Organelles

Class Presentation on Topic 2

4A– IB Biology HL



Definition: Small spherical structures, consisting of two subunits.


ABC – from the HLB textbook

ABC – from the AP Bio textbook

*some sentences may contain the pg. #’s from where the info is derived from.

Angel Alabe/Abbey Currence

Ribosomes structure function

RIBOSOMESStructure & Function

  • -Carry out protein synthesis. (More protein synthesis, more ribosomes found)

  • -One large subunit on top with one small subunit attached to bottom

  • -Occur in all prokaryotic cells and function as sites of protein synthesis

  • -They occur in very large numbers in cells with high protein production, and when numerous, impart a granular appearance to an electron micrograph of the prokaryotic cell.

Larger subunit

Small subunit

Ribosomes structure function contd

RIBOSOMESStructure & Function (contd.)

  • -Ribosomes are complex structures within the plasma membrane, but they have no exterior membrane.

  • -The part of the cell where proteins are made. Made of rRNA and have two subunits (513)

  • -Rough ER has ribosomes on the exterior of the channels (22)

  • -Decode strands of mRNA to produce polypeptides in the space between the two subunits. (204)

Ribosomes structure function contd1

RIBOSOMESStructure & Function (contd.)

  • -Between subunits: binding sites for mRNA and tRNA (site A, P, and E) (204)

    • A: holds rRNA carrying the next amino acid to be added to the polypeptide chain

    • P: holds tRNA carrying the growing polypeptide chain

    • E: site from which tRNA that has lost its amino acid is discharged

Ribosomes contents


  • -Composed of a type of RNA and protein. (22)

  • -Subunits composed of ribosomal RNA (rRNA) molecules and many distinct proteins. (203)

  • -About 2/3 ribosomes mass is rRNA. (203)

Ribosomes characteristics


  • -One large subunit on top w/ smaller one on bottom

    • -Molecules of ribosomes are constructed in the nucleolus of eukaryotic cells and exit the nucleus through the membrane pores. (204)

Ribosomes proteins produced free vs attached

RIBOSOMESProteins Produced: Free vs. Attached

  • -Both structurally identical

  • -Free: suspended in cytosol (cytoplasm)

  • -Bound: attached to outside of endoplasmic reticulum or nuclear envelope

  • Generally make proteins that are destined for insertion into membranes, for packaging within certain organelles (such as lysosomes), or for export from the cell (secretion)

Ribosomes prokaryotic vs eukaryotic cell s ribosomes

RIBOSOMESProkaryotic vs. Eukaryotic Cell’s Ribosomes

  • Euk: Larger and denser than Prok. (22)

    • Subunits equal 80S (22)

    • Animal -Small structures, free in the cytoplasm or associated with the endoplasmic reticulum (ER)

    • Plant –Small (20nm) stuctures which manufacture proteins. May be free in the cytoplasm or associated with the surface of the endoplasmic reticulum

  • Prok: Smaller and less dense than Euk (22)

    • Subunits equal 70S

    • Difference in molecular makeup (204)

Ribosomes 70s ribosomes

RIBOSOMES70S Ribosomes

  • -Prok. Subunits together equal 70S (22)

  • -Euk. Subunits together equal 80S

  • (S= Svedberg units, which indicate the relative rate of sedimentation during high-speed centrifugation) (22)

Ribosomes translation channeling of proteins

RIBOSOMESTranslation & Channeling of Proteins

*addressing codons*

-codons carry the genetic code from DNA to the ribosomes via mRNA. -there are 64 possible codons.

-three codons have no complementary tRNAanticodon ( referred to as stop codons)

-there is a start codon (AUG) that signals the beginning of a polypeptide chain.

-start codon also encodes the amino acid methionine.


– The process of producing a protein once mRNA has been produced from the DNA template. (RNA protein)

  • The process is referred to as translation because it changes the language of DNA to the language of protein

  • The centre of this process is the ribosome.

  • Process involves several phases:

    • Initiation

    • Elongation

    • Translocation

    • Termination


noun /ˈkōˌdän/ 

A sequence of three nucleotides which together form a unit of genetic code in a DNA or RNA molecule

Ribosomes differences between free rer ribosomes

RIBOSOMESDifferences Between Free & rERRibosomes

rER – rough endoplasmic reticulum

  • Free Ribosomesvs.

    • Move freely in the cytoplasm

    • Proteins produced are primarily used within the cell (206)

  • rERRibosomes

    • Attached to the exterior channels of rER

    • Involved in protein synthesis

    • Proteins produced are primarily secreted from the cell or used in lysosomes (206)

Ribosomes translation channeling of proteins contd

RIBOSOMESTranslation & Channeling of Proteins (contd.)


    • The start codon (AUG) is on the 5’ end on all mRNAs.

    • Each codon, other than the three stop codons, attaches to a particular tRNA. The tRNA has a 5’end and a 3’ end like all other nucleic acid strands.

    • The 3’ end of tRNA is free and has the base sequence of CCA which is the site of amino acid attachment.

    • Hydrogen bonds form in four areas because there are complementary bases in the

      single stranded tRNA, which causes the tRNA to fold and tane-on a three dimensional structure.

    • If the molecule is flattened, it has a two dimensional appearance of a clover leaf.

    • One of the loops of the clover leaf contains an exposed anticodon which is unique to each type of tRNA. It’s also the anitcodon that pair with a specific codon of mRNA

Ribosomes translation channeling of proteins contd1

RIBOSOMESTranslation & Channeling of Proteins (contd.)


    • Each of the 20 amino acids binds to the appropriate tRNA due to the action of particular enzyme

    • Because there are 20 amino acids, there are 20 enzymes

    • The active site of each enzyme allows a fit only between a specific amino acid and the specific tRNA.

    • The actual attachment of the amino acid and the tRNA requires energy that is supplied by the ATP.

    • At this point, the structure , structure is called an activated amino acid, and the tRNA may now deliver the amino acid to a ribosome to produce a polypeptide chain.

Ribosomes translation channeling of proteins contd2

RIBOSOMESTranslation & Channeling of Proteins (contd.)


    • The initiation phase are the first steps of the Translation process:

      • When an activated amino acid – methionine attached to a tRNA with the anitcodon UAC – combines with an mRNA strand and a small ribosome unit.

      • The small subunit moves down the mRNA untill it contact the start codon (AUG), this contact starts the translation process.

      • Hydrogen bonds form between the initiator tRNA and the start codon

      • Next, a large ribosomal subunit combines with these parts to form the translation initiation process complex.

      • Joining the initiation complex are proteins called initiation factors that require energy from guanosinetriphosphate (GTP) for attachment. GTP is an energy-rich compound very similar to ATP

Ribosomes translation channeling of proteins contd3

RIBOSOMESTranslation & Channeling of Proteins (contd.)


    Once initiation is complete, elongation occurs

  • Phase involves tRNAs bringing amino acids to the mRNA – ribosomal complex in the order of specified by the codons of the mRNA.

  • Proteins called elongation factors assist in the binding the tRNAs to the exposed mRNA codons at the A site.

  • The initiator tRNA then moves to the P site. The ribosomescatalyse the formation of peptide bonds between adjacent amino acids brought to the polypeptide assembling area.

Ribosomes translation channeling of proteins contd4

RIBOSOMESTranslation & Channeling of Proteins (contd.)


    This phase happens during the elongation phase

    • Involves the movement of the tRNAs from one site of the mRNA to another.

    • First, a tRNA binds with the A site & its amino acid is then added to the growing polypeptide chain by a peptide bond.

    • This causes the polypeptide chain to be attached to the tRNA at the A site.

    • The tRNA then moves to the P site & transfers its polypeptide chain to the new tRNA that moves into the now exposed A site.

    • Empty tRNA is transferred to the E where it’s released. This process occurs in the 5’ to 3’ direction.

    • Therefore, the ribosomal complex is moving along the mRNA toward the 3’ end.

    • Remember that the start codon was near the 5’ end of the mRNA.

Ribosomes translation channeling of proteins contd translocation phase

RIBOSOMESTranslation & Channeling of Proteins (contd.) TRANSLOCATION PHASE

Ribosomes translation channeling of proteins contd5

RIBOSOMESTranslation & Channeling of Proteins (contd.)


    Termination phase completes the translation process

  • Begins when one of the three stop codons appears at the open of A site

  • A protein called a release factor then fills the A site (protein factor does not carry an amino acid).

  • It catalyses the hydrolysis of the bond linking the tRNA in the P site with the polypeptide chain.

  • This frees the polypeptide, releasing it from the ribosome.

  • Ribosome then separates frmom the mRNA & splits into its 2 subunits.

  • Proteins synthesized in this manner have several different destinations.

  • If they are produced by free ribosomes, proteins are primarily used within the cell.

  • If produced by ribosomes bound to the ER, they’re primarily secreted from the cell or used in lysosomes.

Ribosomes translation channeling of proteins contd termination phase

RIBOSOMESTranslation & Channeling of Proteins (contd.) TERMINATION PHASE

Rough endoplasmic reticulum

Rough Endoplasmic Reticulum


  • A membranous system of interconnected tubules and flattened sacs called cisternae.

  • Rough Endoplasmic Reticulum – studded on its outer surface with ribosomes.

Rough endoplasmic reticulum1

Rough Endoplasmic Reticulum


  • It transports materials throughout the internal region to cell.

  • Membrane factory for cells; it grows in place by adding membrane proteins and phospholipids to its membrane

  • It is involved in protein development and transport.

Rough endoplasmic reticulum2

Rough Endoplasmic Reticulum


  • Most secretory proteins in the organelle are glycoprotein (proteins that have carbohydrates covalently bonded to them). The carbohydrates are then attached to the proteins the rough endoplasmic reticulum by specialized molecules built into its membrane.

Rough endoplasmic reticulum3

Rough Endoplasmic Reticulum

Rough Endoplasmic Reticulum

Cell membrane

Cell Membrane

  • Definition: The organelle that “functions as a selective barrier or boundary for every cell, and regulates the sufficient passage of oxygen, nutrients, and wastes to service the entire cell.”

  • Also known as:

    • Membrane

    • Plasma membrane

    • Cell surface membrane

  • Organelles have membranes, too, that are similar in structure

Cell membrane1

Cell Membrane

Cell membrane2

Cell Membrane

Micrograph image of part of a cell:

I = Membrane (of the nuclear envelope)

II = Mitochondrion

Cell membrane phospholipid structure

Cell MembranePhospholipid Structure

  • Structure Overview: There is a bilayer (double layer) in which lipids (fats) stay on the outer part, and proteins pass through the middle among the lipid tails

  • Phospholipids: Made up of glycerol (3 carbon compound)

    • 2 of glycerol carbons are attached to fatty acids

    • 3rd glycerol carbon attached to highly polar organic alcohol (related to phosphate)

Cell membrane3

Cell Membrane

Cell membrane phospholipid structure1

Cell MembranePhospholipid Structure

  • Has a hydrophilic (polar, water soluble) head

  • Has two hydrophobic (nonpolar, water insoluble) tails

  • The tails have a weak bond, causing the cell membrane to be very flexible

  • The heads are connected by hydrogen bonds, and they maintain the structure of the membrane

Cell membrane4

Cell Membrane

Cell membrane5

Cell Membrane

Cell membrane phospholipid s tructure

Cell MembranePhospholipid Structure


  • Found in animal cells ONLY

  • Located in the tails of phospholipids

  • Determines the membrane fluidity

  • Membranes MUST be fluid in order to function properly

  • Consistency is similar to olive oil

  • Temperature change affects fluidity

  • Instead of cholesterol, plant cells use unsaturated and saturated fatty acids

Cell membrane proteins

Cell MembraneProteins

  • Many different varieties – Also known as amino acids

  • Two most prominent types are:

    • Integral proteins

    • Peripheral proteins

Cell membrane proteins1

Cell MembraneProteins


  • Hydrophilic regions – polar amino acids (outer regions)

  • Hydrophobic regions – nonpolar amino acids (central regions)

  • Regulate the entrance and exit of molecules through the cell membrane

I = Integral Protein

Cell membrane proteins2

Cell MembraneProteins


  • Stays on the surface of cell membrane

  • Attached to integral proteins

  • Also attach to glycoproteins (another type )

Cell membrane6

Cell Membrane

I = Glycoprotein

II = Integral protein

III = Hydrophilic phosphate head

Cell membrane7

Cell Membrane

Cell membrane protein functions

Cell MembraneProtein Functions

6 basic functions of proteins:

  • Enzymatic action: relates to metabolic reactions

  • Cell adhesion: when proteins connect (junctions)

  • Cell-to-cell communication: for identification

  • Hormone binding sites

  • Passive transport channels

  • Active transport pumps

Cell membrane transport

Cell MembraneTransport

Two types of transport are:

  • Passive transport: movement due to redistribution for different concentrations, no energy expended

    • Diffusion

    • Osmosis

  • Active transport: movement against concentration gradient, energy is expended (in the form of ATP)

Cell membrane passive transport

Cell MembranePassive Transport

Diffusion: movement of non-water particles from a concentration that is high to one that is low

  • Movement between protein channels (phospholipid molecules)

  • Facilitated diffusion: carrier proteins combine with substances to help with movement – protein shapechanges but no energy is required still

Cell membrane passive transport1

Cell MembranePassive Transport

  • Exam Question Example: Channel Proteins

  • The diagram below shows a channel protein in a membrane. Which parts of the surface of the protein would be composed of polar amino acids?

  • A.I and II only

  • B.II and III only

  • C.III and IV only

  • D.I and IV only

    (Answer is A)

Cell membrane passive transport2

Cell MembranePassive Transport

Cell membrane passive transport3

Cell MembranePassive Transport


  • Happens along the concentration gradient

  • Involves ONLY water molecules

  • Happens with partially permeable membranes

  • Movement caused by concentrationdifference inside and outside the cell membrane

  • Goal of passive transport is to reach equilibrium on both sides

Cell membrane passive transport4

Cell MembranePassive Transport


  • Hyperosmotic – higher concentration

  • Hypo-osmotic – lower concentration

  • Water moves from

    hypo-osmotic → hyperosmotic

  • Iso-osmotic – equilibrium, no movement

Cell membrane passive transport5

Cell MembranePassive Transport

Osmosis: influencing factors of substances that are being transported are…

  • Size – small = easy movement

    large = difficult movement

  • Charge – nonpolar = easy movement

    polar = difficult movement

Cell membrane passive transport6

Cell MembranePassive Transport

(Partially permeable)

Uses aquaporins (proteins with specialized water channels)

Trying to achieve equilibrium (iso-osmotic)

Cell membrane active transport

Cell MembraneActive Transport

  • Does require energy in the form of ATP

  • Moves against a concentration gradient that needs energy

  • Process helps cell maintain equal concentrations inside and outside the membrane

Cell membrane active transport1

Cell MembraneActive Transport

Sodium-potassium pump: (way for moving these ions)

  • Specific protein in cell membrane binds to three sodium ions from inside the cell

  • Binding of sodium ions causes phosphorylation (the activation of the protein enzymes through the addition of PO4-3 from the phosphate molecule from the AT

  • Phosphorylation causes protein to change shape and expel sodium ions that were inside the protein to outside the cell

  • 2 potassium ions enter the protein from outside the cell which causes the phosphate to be released

  • When the phosphate is released, protein restores to its original shape and the potassium ions are released into cell

Cell membrane active transport2

Cell MembraneActive Transport

Cell membrane endocytosis exocytosis

Cell MembraneEndocytosis & Exocytosis

  • Endocytosis: process that allows macromolecules to enter the cell

  • Exocytosis: process that allows macromolecules to leave the cell

  • In endocytosis, portion of membrane is pinched to surround a particle, and a vesicle forms leading to the cytoplasm

  • Vesicle allows protein to eventually reach nucleus

Cell organelles cell wall

Cell Organelles - Cell Wall

Class Presentation on Topic 2

4A– IB Biology HL

By: Robert Jennings

Cell wall

Cell Wall

  • The cell wall is a semi-rigid structure composed mainly of cellulose, and its purpose is to give the cell structure and protection.

Structure composistion cell wall

Structure/Composistion-Cell Wall

  • Consist of three layers.

  • Middle lamella

  • Formed during cell division

  • Makes up outer wall of cell

  • Composed of proteins and pectic compounds.

  • Primary wall

  • Formed after middle lamella.

  • Consist of rigid skeleton made of cellulose microfibrils embedded in a gel-like matrix composed of pectic compounds, hemicellulose, and glycoproteins.

  • Secondary wall

  • After cell enlargement is completed

  • Very rigid and provides incredible strength.

  • Layered and made of cellulose, lignin, and hemicellulose.

Function cell wall

Function-Cell Wall

  • Determines the shape of the particular cell.

  • Provides strength to the cell but is still somewhat flexible.

  • Controls the turgor pressure in a cell. Turgor is the pressure applied to the cell from the constituents inside it.

  • Since the cell wall is permeable it allows for proteins and other small molecules to come in and out of the cell.

  • Protects cells from pathogens and microorganisms.

  • Reserves carbohydrates that can be used in times of need.

Vesicles cell wall

Vesicles-Cell Wall

  • Vesicles are smooth pieces of endoplasmic reticulum or ER that break off and transport things such as proteins throughout the cell.

  • Vesicles are storage organelles.

  • Vesicles, carry molecules that are too large to pass directly through the membrane to destinations outside of the cell.

  • Vesicles form when coat proteins wrap themselves around large molecules. This spherical product then buds out of the ER (endoplasmic reticulum) and is carried like cargo out of the cell’s membrane.

Miscellaneous cell wall

Miscellaneous-Cell Wall

  • Prokaryotic cells have a cell wall as well as plant cells.

Lysosome structure


  • Composed of:

    • Membrane

    • Proteins and Enzymes

If the lysosome stops or explodes, the cell will break down

Lysosome function


  • Scientifically, lysosomes are organelles that contain digestive enzymes. So, in other words, the lysosomes are essentially the stomach of the cell.

  • Intracellular digestive centers that derive from the Golgi apparatus

  • The enzymes that lysosomes have can breaks down the substances within the cell



The lysosome performs it’s job

by helping digest the microbe



  • Collects, packages, modifies, and distributes materials synthesized in the cell

  • Is the post office of the cell

  • Tells products where to go in or out of the cell.



  • Main body is cisternae. Which are flat and stacked on top of each other. Products travel through cisternae.

  • Two sides. Cis side is close to the rough ER. Trans side.

  • Vesicles go in one side and come out the other.

  • Modifies Vesicles by adding enzymes or removing sugar and adding it own.

Class presentation on topic 2 4a ib biology hl


Class Presentation on Topic 2

4A– IB Biology HL

Nucleus function

Nucleus: Function

  • *The main function of the nucleus is to regulate activity within a cell.

  • *Ex. Aids in reproduction

Nucleus structure

Nucleus: Structure

* Bordered by a double membrane, nuclear envelope.

* Contains a nucleolus

Nucleus contents

Nucleus: Contents

* Contains most of the cell’s DNA *

Nucleus prokaryotic vs eukaryotic

Nucleus: Prokaryotic vs. Eukaryotic:

*Prokaryotic cells do NOT have a nucleus.

* Eukaryotic cells DO have a nucleus.

Nucleus nuclear membrane

Nucleus: Nuclear Membrane

  • *Double layered structure that separates nucleus from cytoplasm* Itcontains pores that allow communication with cytoplasm

Nucleus locations

Nucleus: Locations

* A nucleus is located in the center of a cell.

Nucleus micrograph

Nucleus: Micrograph

  • * A Micrograph is a photo taken by a microscope!

Nucleus dna and rna

Nucleus: DNA and RNA

* DNA carries the genetics of a cell and consists of thousands of genes

* The RNA is processed so that non-coding parts are removed. After this, the RNA is removed from the nucleus.

Nucleus haploid nucleus diploid nuclei

Nucleus: Haploid nucleus + Diploid nuclei

In cell division:

  • *Haploid nuclei contain only half of the number of chromosomes (23 chromosomes)

  • * Diploid nuclei contain both pairs of chromosomes (which is 46 chromosomes)




Sarah Liles, Natashia Gavarrete, and Matthew Juve

Period 4A

IB Biology Year 1 HL



  • Structure Within (Contents):

    • Rod-shaped organelles that appear throughout the cytoplasm.

    • Have their own DNA.

      • Circular chromosome similar to that in bacteria cells, allowing for autonomy within the cell.

    • Has a smooth outer membrane. The inner membrane is a semi-fluid substance called a matrix, and lies between the two membranes.

    • Cristae provides a huge internal surface area for the chemical reactions of the mitochondria to occur.



  • Structure:

    • an outer membrane that encloses the entire structure

    • an inner membrane that encloses a fluid-filled matrix

    • between the two is the intermembrane space

    • the inner membrane is elaborately folded with shelflikecristae projecting into the matrix.

    • a small number (some 5–10) circular molecules of DNA



Prokaryotic Cell

  • Uses in prokaryotic cells:

    • They are not present in prokaryotic cells.

  • Uses in eukaryotic cells:

    • the energy producing structures of Eukaryotic cells and supply the cells with ATP.

    • Structures which produce the cell’s energy.

    • Powerhouses of the cell.

Eukaryotic Cell



  • Functions:

    • Main function: production of energy in the form of adenosine triphosphate (ATP)

    • Performs the process of programmed cell death. It occurs during development as the organism is pruning away unwanted, excess cells.

    • involved in building, breaking down, and recycling products needed for proper cell functioning.



  • Mitochondria’s role in cellular respiration:

    • known as the powerhouses of the cell.

    • They are organelles that act as a digestive system that takes in nutrients and breaks them down.

    • This process creates energy for the cell.

    • By producing this nutrients and power it contributes to creating cell energy other wise known as cellular respiration.

    • The Mitochondrion's perfect shape allows for a good place for cellular respiration to occur, and maximize the effort given.



  • Acetyl-CoA: produced in mitochondria through the oxidation of fats.

    • Pyruvate is converted to Acetyl Coenzyme (CoA) via active transport when entering the mitochondria.

    • The entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to coenzyme while transporting through the organelle.



  • Carries out key reactions in the cells of eukaryotes.

  • ATP Synthetase occurs in these organelles.

  • It is the location of Chemiosmosis.

    • The diffusion of ions across a selectively-permeable membrane. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration

  • Electron Micrograph

    • Mitochondrion appear as bacteria sized ellipses.

    • Vary in size and width, but this is hard to see on a two dimensional electron micrograph.



  • Krebs cycle- Cycle that accounts for the oxidation of carbohydrates in prokaryotes and eukaryotes.

  • Mitochondria produce the ATP in the Krebs cycle in eukaryotes.

  • There are no mitochondria in bacteria.



  • Mitochondria vs. chloroplasts

    • Both are circular in shape.

    • Both are involved in ATP production.

    • Chloroplasts are slightly larger.

    • Mitochondrion generate ATP with glucose during cell respiration.

    • Chloroplasts generate ATP through sunlight.



Exam Question Example #1

The electron micrograph below shows part of several pancreatic islet cells.

(a) Identify the structures labelled I, II and III in the micrograph above and give a role for each one.(3)

(b) (i) Using the letter A, identify one location on the micrograph where transcription takes place. (1)

(ii)Using the letter B, identify one location on the micrograph where chemiosmosis occurs. (1)



Exam Question Example #1




Storage vesicles


  • *Transcription takes place

  • ** Chemiosmosis

(Rough) Endoplasmic Reticulum



Exam Question Example #2

The electron micrographs below show mitochondria in longitudinal section. The mitochondrion in A is from a bat pancreas cell and that in B is from a mouse liver cell.(Next Slide)

(a)Annotate the micrographs to show two similarities in the structure of the mitochondria. (2)

(b)The mitochondria differ in size. State two other differences that are visible in the mitochondria. (2)

(c)Predict, with two reasons, which of the mitochondria would have been able to produce ATP at a greater rate.




Exam Question Example #2


  • BAT

  • Similarities






Arrangement of cristae

Density of cristae

Amount of matrix granules/any reference to dark dots *ribosomes not accepted

Which mitochondria would have been able to produce ATP at a greater rate & why:


Larger size/volume

Greater surface area of cristae/more cristae

Closeness of mitochondria in mouse reduces rate



Exam Question Example #7

(a)Distinguish between the terms resolution and magnification when applied to electron microscopy. (2)

The electron micrograph below shows part of a cell. (Next Slide)

(b)Identify the structures labelled I and II. (2)

(c)State one function of the structure labelled II. (1)

(d)Deduce, with a reason, whether this cell is eukaryotic or prokaryotic. (1)

(Total 6 marks)



Exam Question Example #7


resolution: separate points / focus clearly / greater detail / clarity;magnification: size of image / view / picture

  • Function of mitochondrion (II):

  • aerobic respiration;correct specific reaction / pathway occurring in mitochondria / ATP production; Do not accept “energy production” alone.


internal membranes / membrane bound organelles / presence of mitochondria / double nuclear membrane;

I: membrane / (nuclear) envelopeII: mitochondrion / mitochondria



  • Approximately the same size as a bacterial cell

  • The parts

    • -Thylakoid: flat shaped membrane sacs that absorbed light for photosynthesis.

    • -Stroma: Contain the chloroplast DNA and ribosomes as well as many enzymes that aid in photosynthesis

    • -Double membrane: two membranes that separate the contents from the cytosol. Also create a small space between the membranes.



  • Contains enzymes in the Stroma which helps complete photosynthesis.

  • - RuBP carboxylase enzyme- catalyzes the first step of the Calvin Cycle.

  • Main function is photosynthesis

  • The Calvin Cycle- In the Calvin Cycle, the enzymes of the chloroplast are in the stroma.

  • Tylakoids of chloroplasts get positive protons using energy obtained from light sources, thus the small volume size is advantageous to concentrate protons more rapidly.

  • Plastids

  • Have three distinct parts: the intermembrane space, the stroma, and the thylakoid space.






-Same size

-Double membranes

- 70S ribosomes



  • Chlorophyll:

    • Green pigment

    • Plants are green due to the green pigment of chlorophyll (used in photosynthesis).

    • Absorbs violet-blue and red colors and reflects green light (visible light)

    • Chemical structure of chlorophyll

Works cited

Works Cited

  • http://learn.genetics.utah.edu/content/begin/cells/vesicles/

  • http://biology.clc.uc.edu/courses/bio104/cells.htm

  • AP Edition Biology Textbook.

  • Biology HL Textbook.

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