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Honors Biology: Chapter 4. A Tour of the Cell. The Art of Looking at Cells Artists have long found inspiration in the visual richness of the living world Conversely, scientists use art to illustrate their findings Micrographs show structures as scientists see them

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honors biology chapter 4

Honors Biology: Chapter 4

A Tour of the Cell

slide2
The Art of Looking at Cells
    • Artists have long found inspiration in the visual richness of the living world
    • Conversely, scientists use art to illustrate their findings
      • Micrographs show structures as scientists see them
      • Drawings can emphasize details
biology is a visual science
Biology is a visual science

Wasily Kandinsky (1866-1944)

– is it based on a cell?

Santiago Ramon y Cajal (1852-1934) anatomist

- Nerve cells in the retina

contributions to the cell theory
Contributions to The Cell Theory
  • Zaccharias Jansen – first compound scope
  • Robert Hooke 1660s – term for “cells”
    • Saw cork cell walls
    • Tiny compartments
    • Called them “cells”
anton von leeuwenhoek
Anton von Leeuwenhoek
  • Anton von Leeuwenhoek 1660s
    • first high-mag microscope
    • living cells, bacteria
    • Pond water, blood, saliva
other cell discoveries
Other cell discoveries
  • Robert Brown – 1830s
  • nucleus in all cells
  • Matthias Schleiden 1830s
    • all plants made of cells
  • Theodore Schwann 1830s
    • all animals made of cells
  • Rudolf Virchow 1850s
    • new cells come from cell division
the cell theory
The Cell Theory
  • All organisms are made of one or more cells
  • The cell is the basic unit of life. Cells that form part of a larger organism still do their own life processes.
  • All cells come from pre-existing cells
4 2 why are all cells small
4.2 Why are all cells small?

Cells vary in size and shape

  • Must be big enough to contain raw materials and molecules needed by cell
  • Must be small enough to have fast exchange with environment

Surface area must be large compared to volume

5

cells have a large surface to volume ratio
Cells have a large Surface-to-Volume Ratio

size increases 2Xarea increases 4X volume increases 8X

6

two basic kinds of cells
Two basic kinds of cells

ProkaryoticEukaryotic

small and simple larger and more complex

no nucleus nucleus

bacteria all other organisms

Both have: DNA & complex chemicals

cell membrane cytoplasmribosomes

two kinds of cells small and large
Two kinds of cells – small and large

Bacteria (purple) in animal cell (pink)

le 4 3a

LE 4-3a

Prokaryotic cell

Two kinds of cells

Simple and complex

Nucleoid

region

Colorized TEM 15,000

Nucleus

Organelles

Eukaryotic cell

prokaryotic cells before nucleus
Prokaryotic cells“before nucleus”
  • Very small (1-10mm)
  • No nucleus or other membrane-bound organelles
  • DNA in nucleoid region in cytoplasm
all prokaryotes have
ALL prokaryotes have

1. Cell (plasma) membrane

  • Encloses cytoplasm, selectively permeable
  • Controls what enters and leaves cell

2. Nucleoid

  • Region containing DNA in a chromosome

3. Cell wall – various kinds of polysaccharides

  • Outside cell membrane
  • Cell shape and protection
some prokaryotes have
SOME prokaryotes have

4. Capsule – protective layer

  • Slimy or sticky coating, outside cell wall

5. Pili – extensions of cytoplasm and membrane

  • to attach to other cells, pass signals

6. Prokaryotic flagella – for movement

7. Plasmids – small rings of DNA

  • For sexual reproduction
  • have their own genes
slide17

Some prokaryotic (bacterial) cells

Common shapes of bacteria

eukaryotes true nucleus
Eukaryotes “true nucleus”
  • 4.4 Eukaryotic cells are partitioned into compartments
    • Larger than prokaryotic (10-100 m)
    • Many organelles – tiny “organs”, specific functions
    • Most organelles are enclosed by membrane
      • Compartments - different metabolic processes
      • Keeps chemistry inside organelle separate from rest of cell
      • Enzymes often are parts of the membranes, greatly increase surface for reactions
eukaryotic cells
Eukaryotic Cells

The cell is like a city – every part has a job to do. Together these parts keep the cell alive.

le 4 4a

LE 4-4a

Smooth

endoplasmic

reticulum

Rough

endoplasmic

reticulum

Nucleus

Flagellum

Not in most

plant cells

Lycosome

Centriole

Ribosomes

Peroxisome

Golgi

apparatus

Microtubule

Intermediate

filament

Plasma membrane

Cytoskeleton

Microfilament

Mitochondrion

le 4 4b

LE 4-4b

Rough endoplasmic

reticulum

Nucleus

Ribosomes

Smooth endoplasmic

reticulum

Golgi

apparatus

Microtubule

Intermediate

filament

Central

vacuole

Cytoskeleton

Not in

animal

cells

Microfilament

Chloroplast

Cell wall

Mitochondrion

Peroxisome

Plasma membrane

cytoplasm
Cytoplasm
  • Cytoplasm: Watery solution outside nucleus
  • Contains organelles, each has a function
  • Many dissolved substances for metabolism
  • Site for chemical reactions

Cytoplasm and nucleus work together

4 5 nucleus the cell s genetic control center
4.5 Nucleus: the cell's genetic control center
  • Has MOST of a cell’s DNA
  • DNA in chromosomes
  • Chromatin - loose, thread-like form of chromosome in
  • non-dividing cell
  • Controls cell by directing synthesis of proteins

Also contains nucleolus – makes ribosomes

structures in a nucleus
Structures in a nucleus
  • Nucleolus – makes ribosomes

chromatin

Nuclear pores

Nuclear membrane

nucleolus

nuclear envelope
Nuclear Envelope
  • Double-layered membrane surrounding nucleus
  • Many pores for molecules to pass through
  • Selectively permeable – controls what moves in and out of nucleus
nuclear pores
Nuclear pores

Control flow of materials in and out of nucleus

4 6 endomembrane system
4.6 Endomembrane System
  • A collection of membranous organelles
  • - divide the cell into compartments
    • - work together to synthesize, store, and export molecules
  • Example: Endoplasmic reticulum (ER)
      • Continuous network of flattened sacs and tubes throughout cell
le 4 5

LE 4-5

Nucleus

Chromatin

Two membranes

of nuclear envelope

Nucleolus

Pore

Rough

endoplasmic

reticulum

Ribosomes

4 8 rough endoplasmic reticulum
4.8 Rough Endoplasmic Reticulum
  • Rough ER makes membrane and proteins
    • Ribosomes on membrane make proteins
    • RER modifies proteins made by ribosomes and transports to other parts of cell
    • Some sent to Golgi body for further processing
organelles that build proteins
Organelles that Build Proteins

Ribosomes

Make proteins, use instructions in DNA

Made of RNA and protein

Made in nucleolus, move to cytoplasm and rough ER

le 4 7

LE 4-7

Smooth ER

Rough ER

Nuclear

envelope

Ribosomes

Smooth ER

Rough ER

TEM 45,000

le 4 8

LE 4-8

Transport vesicle

buds off

Secretary

(glyco-) protein

inside trans-

port vesicle

Ribosome

Sugar

chain

Glycoprotein

Polypeptide

Rough ER

4 7 smooth endoplasmic reticulum
4.7 Smooth Endoplasmic Reticulum

No ribosomes on membrane

  • Smooth ER has a variety of functions
      • Synthesizes lipids
      • In liver cells, processes materials such as toxins and drugs
      • In muscle cells, stores and releases calcium ions needed for muscle contraction
4 9 golgi body
4.9 Golgi Body
  • The Golgi apparatus finishes, sorts, and ships cell products
    • Stacks of flattened membrane sacs
    • Receives and modifies proteins from ER
    • Sorts, packages into tiny vesicles
    • Final products may be used inside cell – ex. Lysosomes
    • Some exported – ex. Hormones, neurotransmitters
le 4 9

LE 4-9

Golgi

apparatus

Golgi apparatus

“Receiving” side of

Golgi apparatus

Transport

vesicle

from ER

New vesicle

forming

“Shipping”

side of Golgi

apparatus

TEM 130,000 

Transport

vesicle from

the Golgi

4 10 lysosomes digestive compartments
4.10 Lysosomes –digestive compartments

Lysosomes are sacs of enzymes that form from the Golgi apparatus

  • Break down wastes and worn-out cell parts
  • Recycle molecules the cell can use
  • In protozoans, bind to food vacuole to digest food
  • In white blood cells, destroy bacteria that have been ingested
  • In development, removes tissues no longer needed
  • Cell death, when cell is damaged beyond repair

Animation: Lysosome Formation

le 4 10a

LE 4-10a

Rough ER

Transport vesicle

(containing inactive

hydrolytic enzymes)

Plasma

membrane

Golgi

apparatus

Engulfment

of particle

Lysosome

engulfing

damaged

organelle

“Food”

Lysosomes

Food

vacuole

Digestion

le 4 10b

LE 4-10b

Lysosome

Nucleus

Lysosomes are stained

in this slide

TEM 8,500 

slide40

Lysosome containing

two damaged organelles

Mitochondrion fragment

TEM 42,500 

Peroxisome fragment

4 11 abnormal lysosomes
4.11 Abnormal lysosomes
  • Lysosomal storage diseases can be fatal
    • Result from an inherited lack of one or more lysosomal enzymes
    • Interfere with various cell functions
    • Ex. Tay-Sachs Disease, Pompe’s disease
peroxisomes break down peroxide
Peroxisomes – break down peroxide

Peroxisomes (microbodies)

– break down hydrogen peroxide, made in cell reactions

- other chemical functions in certain cells

- peroxisome disorders include ALD

4 12 vacuoles store substances
4.12 Vacuoles store substances

Food vacuoles in paramecium

slide44

Plant Cell Vacuole

    • Large, central vacuole
    • Stores water and substances needed for photosynthesis
    • Enzymes to recycle molecules (no lysosomes in plant cells)
le 4 12a

LE 4-12a

Nucleus

Chloroplast

Central

vacuole

Colorized TEM 8,700 

contractile vacuole
Contractile Vacuole
  • In some one-celled organisms that live in fresh water
  • Water enters cell from environment
  • Vacuole pumps out excess water
  • Keeps homeostasis
le 4 12b

LE 4-12b

Nucleus

LM 650

Contractile

vacuoles

review membrane organelles
Review Membrane Organelles
  • 4.13 A review of the endomembrane system
    • The various organelles of the endomembrane system are interconnected structurally and functionally
    • ER is in direct contact with nuclear membrane
    • Membrane vesicles transport products from ER to Golgi body, and from Golgi to cell surface

Animation: Endomembrane System

le 4 13

LE 4-13

Transport vesicle from

Golgi to plasma membrane

Transport vesicle

from ER to Golgi

Rough ER

Plasma

membrane

Nucleus

Vacuole

Lysosome

Nuclear envelope

Golgi apparatus

Smooth ER

organelles that capture and release energy
Organelles that capture and release energy

4.14 Chloroplasts –site for photosynthesis

Chlorophyll pigment in membrane absorbs sunlight

Convert solar energy into chemical energy of food

Plants

Algae

le 4 14

LE 4-14

  • Chloroplasts have inner membrane compartments
  • Each is site for different stage of photosynthesis

Stroma

Chloroplast

Inner and outer

membranes

Granum

TEM 9,750

Intermembrane

space

chloroplasts in plants and algae
Chloroplasts – in plants and algae

Some protists have chloroplasts

other plastids in plants
Other plastids in plants

Leukoplasts

store starch

Chromoplasts

store other pigments

-flowers, fruits, seeds

In potato

In red pepper

4 15 mitochondria powerhouse of the cell
4.15 Mitochondria – powerhouse of the cell
  • Site for Cell respiration – converts chemical energy stored in food into ATP for cellular work
    • ATP – energy molecule used by all organisms for cell activities

Mitochondria - two membrane compartments

Each location is site for different stage of glucose breakdown

le 4 15

LE 4-15

Mitochondrion

Outer

membrane

Intermembrane

space

Inner

membrane

Cristae

TEM 44,880

Matrix

mitochondria and chloroplasts are different from other organelles
Mitochondria and Chloroplasts are different from other organelles
  • double-layered membrane organelles

- inner membrane deeply folded/layered

- large surface area for fast chemical processes

  • have their own DNA and ribosomes

- can self-replicate as needed

- make their own enzymes for reactions

how do plant and animal cells differ
How do plant and animal cells differ?
  • Both have most of the same organelles except:
  • Plant cells also have:
  • 1. rigid cell wall, contains cellulose –
  • - protects photosynthetic tissue inside
  • 2. chloroplasts – do photosynthesis
    • 3. large central vacuole – stores water and
    • minerals for photosynthesis, wastes
    • Animal cells have:
  • 1. centrioles – aid in cell division
  • 2. lysosomes – contain hydrolytic enzymes
  • 3. some have flagella or cilia
cytoskeleton
Cytoskeleton
  • 4.16 The cell's internal skeleton helps organize its structure and activities
    • Protein framework inside cell
    • Attaches to cell membrane to keep cell shape
    • Anchor organelles
    • Transports materials inside cell
    • Two kinds: microfilaments and microtubules
microfilaments
Microfilaments

Microfilaments

  • Rods of globular proteins
  • Enable cells to change shape and move
  • Cytoplasmic streaming
intermediate filaments
Intermediate filaments
  • Ropes of fibrous protein
  • Reinforce the cell and anchor some anchor some organelles
  • Hollow tubes of globular proteins
  • Give the cell rigidity
  • Anchor organelles and act as tracks for organelle movement
  • Make centrioles, cilia and flagella

Microtubules

proteins in the cytoskeleton
Proteins in the cytoskeleton

Rods of globular proteins

Cells can move, change shape

Stretch and contract

Hollow tubes of globular proteins

Anchors organelles, tracks for movement of materials

Rigid shape

Ropes of fibrous proteins

Anchors some organelles

Reinforces cell

cytoskeleton seen with fluorescent dyes
Cytoskeleton – seen with fluorescent dyes

Microtubules- blue; microfilaments – yellow; chromatin - green

cytoskeleton1
cytoskeleton

The cytoskeleton, a network of protein fibers, crisscrosses the cytoplasm of eukaryotic cells, providing shape and mechanical support. The cytoskeleton also functions as a monorail to transport substances around the cell. A cell such as an amoeba changes shape by dismantling parts of the cytoskeleton and reassembling them in other locations.englishpia.co.kr/main/?page=board&act=view

microfilaments enable cytoplasmic movement
Microfilaments enable cytoplasmic movement
  • Cytoplasmic streaming (cyclosis) moves substances around inside a cell
  • - Some cells can move by pseudopods
4 17 microtubules make cilia and flagella
4.17 Microtubules make cilia and flagella
  • Eukaryotic cilia and flagella are locomotor appendages that protrude from certain cells
      • Move whole cells or materials across the cell surface

Video: Paramecium Cilia

Animation: Cilia and Flagella

cilia and flagella
Cilia and Flagella

Microtubules extend from cell surface, covered by membrane

  • Cilia – short, many, like “oars”
    • Ex. line air passages in body - cover Paramecium
  • Flagella – longer, one or a few, move like a “whip”
    • Ex. Human sperm, euglena
how do cilia flagella move
How do cilia & flagella move?

flagellum

Paired tubules

9 + 2 array

proteins between pairs cause bending

Centrioles and basal bodies have a different tubule pattern 9 X 3

– don’t bend

Basal body – anchors flagellum

cilia and flagella move when microtubules bend
Cilia and flagella move when microtubules bend

Movement of protein arms (dynein) bends microtubules

centrioles and spindle fibers microtubules
Centrioles and Spindle Fibers – microtubules
  • Help in cell division
  • Centrioles (only in animal cells)
    • Organize spindle fibers
    • Spindle fibers (in all eukaryotic cells)
      • Organize and separate chromosomes when cell divides
centrioles
Centrioles
  • Help organize chromosomes for cell division

9 X 3 arrangement

of microtubules

Anchor mitotic spindle in animal cells

cell surfaces and junctions
CELL SURFACES AND JUNCTIONS
  • 4.18 Cell surfaces protect, support, and join cells
    • Cells interact with their environments and each other through their surfaces
    • Many cells are protected by layers outside the cell membrane
      • Prokaryotes –cell wall and sometimes a capsule
      • Eukaryotes – some have cell walls (plants, fungi, and many protists)
        • Multicellular – cells must organize and communicate
plant cell walls provide protection and support
Plant cell walls – provide protection and support
  • Plant cell walls
    • Mostly cellulose, in layers, forms a rigid mesh
    • Sticky saccharides glue cells together
    • Connect by open channels, plasmodesmata
      • Cell membranes and cytoplasm are continuous between adjacent cells
      • Easy transfer of water and nutrients
      • Chemical messages
le 4 18a

LE 4-18a

Walls

of two

adjacent

plant cells

Vacuole

Plasmodesmata

Layers

of one plant

cell wall

Cytoplasm

Plasma membrane

plant cell walls
Plant cell walls

Middle lamella – between walls of two plant cells

animal cell junctions
Animal Cell Junctions

Cells are surrounded by an extracellular matrix that binds cells together into a tissue

Cell junctions:

  • Tight junctions - bind cells into leakproof sheets (ex. Intestine lining)
  • Anchoring junctions - link cells into strong tissues (ex. muscle, skin)
  • Gap junctions – open channels allow substances to flow from cell to cell (ex. Heart muscle, embryo)
le 4 18b

Tight junctions

Anchoring junction

Gap junctions

Extracellular matrix

Space between cells

Plasma membranes of adjacent cells

LE 4-18b

TIGHT JUNCTION

No leaks - protect surrounding tissue

- ex. Intestine wall

  • ANCHORING JUNCTION
  • Connect cytoskeleton of adjacent cells
  • strong, flexible tissue; stretch, move
  • Ex. Skin, muscle

GAP JUNCTION

Open channels – cells communicate

- share needed molecules

slide83

Animation: Tight Junctions

Animation: Desmosomes

Animation: Gap Junctions

endosymbiosis theory lynn margulis
Endosymbiosis Theory – Lynn Margulis

Prokaryotes in various sizes, some lost cell wall

Larger prokaryotes ate smaller ones

Some were not digested but became part of cell

Might have survival advantage

Ex. Make its own food; , use energy more efficiently

  • Evidence to support theory
    • Both chloroplasts and mitochondria have their own DNA and ribosomes – chemically like prokaryotic DNA and ribosomes
    • Can self-replicate
    • May have once been separate organisms
functional categories of organelles
FUNCTIONAL CATEGORIES OF ORGANELLES
  • 4.19 Eukaryotic organelles comprise four functional categories
    • Eukaryotic organelles fall into four functional categories that work together to produce the cell's emergent properties
      • Manufacturing
      • Breakdown
      • Energy processing
      • Support, movement, and communication between cells