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Cytology - PowerPoint PPT Presentation

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Cytology. Cytology = The study of cells Cell = the structural and functional unit of all living things. Cell Organelles. Organelles = “tiny organ” = carry out the life processes of the cell. * each organelle has a specific function. Cell Organelles (cont’d). Nucleus

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= The study of cells


= the structural and functional unit of all living things.

Cell organelles
Cell Organelles


= “tiny organ”

= carry out the life

processes of the cell.

* each organelle

has a specific function.

Cell organelles cont d
Cell Organelles (cont’d)

  • Nucleus

    - surrounded by the nuclear envelope

    - double membrane, with pores

    = controls what enters/exits the nucleus

    - contains the genetic material


DNA = deoxyribonucleic acid

- model of DNA was discovered by 2 scientists = Watson and Crick

- found to be a double stranded helix

- each strand is made up of alternating sugars and phosphate groups.

- attached to the sugars are base pairs that fit together like pieces of a puzzle

Dna cont d
DNA (cont’d)

  • Base pairs:

    - A = T

    - C = G

  • 1 strand reads: A other strand?





Organelles cont d
Organelles (cont’d)

  • in the cell, DNA is located on the chromosomes

    = 46 chromosomes in the average human cell

    = 23 in the gametes

    = sex cells

Organelles cont d1
Organelles (cont’d)

  • Nucleolus

    - dark area of nucleus

    - contains rRNA (ribosomal)

    = makes RIBOSOMES

Organelles cont d2
Organelles (cont’d)

  • Ribosomes

    - passes through nuclear envelope into cytoplasm ( )

    - site of protein synthesis

    - strings amino acids together to form proteins

    - can be free-floating or attached to another organelle.

Organelles cont d3
Organelles (cont’d)

  • Endoplasmic Reticulum (ER)

    - 2 types;

    1. RER = Rough ER

    - has ribosomes attached

    - helps make proteins

    2. SER = Smooth ER

    - no ribosomes attached

    - sends proteins out from ER

Organelles cont d4
Organelles (cont’d)

  • Golgi Apparatus

    - flattened stacks of membranes in the cell

    - modifies, packages, then ships proteins out of the cell in a vesicle

Organelles cont d5
Organelles (cont’d)

  • Mitochondria

    - “power house” of the cell

    - supplies energy to the cell (ATP)

    - breaks down food to form ATP in a process called Cellular Respiration

Organelles cont d6
Organelles (cont’d)

  • Lysosomes

    - digests/break-down wastes in the cell.

  • Centrioles

    - aid in cell reproduction

  • Cytoskeleton

    - gives support/shape to the


Organelles cont d7
Organelles (cont’d)

  • Plasma Membrane

    - protective barrier around the cell.

    - double layer made up of phosphates and lipids

    - controls what enters and exits the cell

Plant organelles
Plant Organelles

  • Plastids

    - produce sugar in plants

    3 types:

    1. Chloroplasts

    - contain chlorophyll

    = green pigment that captures sunlight as energy for plants

Plant organelles cont d
Plant Organelles (cont’d)

2. Chromoplasts

- contain red, orange, yellow pigments that give flowers and fruits their color.

3. Leucoplasts

- colorless plastid

- convert sugar to starch

- better energy storage form

Plant organelles cont d1
Plant Organelles (cont’d)

b. Vacuoles

- store materials

c. Cell Wall

- in plants and fungi (NOT in animals!)

- outside plasma membrane

- protects and supports the cell.

- made up of cellulose (rigid/hard)

Movement of material in a cell
Movement of material in a cell

Molecules are in constant motion –

This energy of motion is called:


- molecules move in a straight line, until it strikes another molecule

- decrease area = increase collisions

- molecules move until they all have an = amount of space.

Passive transport
Passive Transport

Passive Transport

- movement of molecules WITHOUT using any energy from the cell.

- the cell membrane is SELECTIVELY PERMEABLE to some molecules.

= allows certain molecules to pass through. (water, oxygen, CO2, etc)

Passive transport1
Passive Transport

Permeability of an object depends on:

1. Size – (sugar/starch)

2. Charge – (+) or (-)

3. Solubility – ability to be dissolved in water

Passive transport2
Passive Transport

  • Diffusion

    = movement of MOLECULES from an area of high concentration to an area of low concentration.

    ex; - sugar in tea

    - kool-aid

    - tea bags

    - odors

Passive transport3
Passive Transport

  • Osmosis

    = the movement of WATER from an area of high concentration to an area of low concentration.

    - causes osmotic pressure in cells

    = pressure change as result of water moving in or out of the cell.

Passive transport cont d
Passive Transport (cont’d)

  • Facilitated Diffusion

    - increase the rate of diffusion by using carrier proteins in the cell membrane.

Passive transport4
Passive Transport

  • Molecules will continue to move in and out until equilibrium is reached.

    = rate of molecules leaving the cell is = to the rate of molecules entering the cell.

Solution types
Solution types

3 types of solutions are possible when compared to the cell.

  • Isotonic Solution

    = number of solutes in fluid is = to the number of solutes in cell

Solutions cont d
Solutions (cont’d)

  • Hypertonic Solution

    = solution contains a higher number of solutes than the cell

    - solutes move into cell, water moves out

    - results in cell shriveling

Solutions cont d1
Solutions (cont’d)

  • Hypotonic Solutions

    = solution contains a lower number of solutes than the cell

    - solutes move out of the cell, water moves into the cell.

    - results in cell swelling/expanding.

Active transport
Active Transport

Active Transport

- movement of molecules into or out of the cell using cellular energy (ATP)

3 types:

1. Carrier Mediated Active Transport

- use of carrier proteins (like FD)

- movement from low concentration to high, and uses energy.

Active transport1
Active Transport

  • Endocytosis

    - transporting substances into the cell

    a. Pinocytosis

    - membrane surrounds molecule, forms vesicle and pinches off into cell.

    b. Phagocytosis

    - for larger particles

    - cell surrounds and engulfs molecule

Plant cells
Plant Cells

  • plant cells are surrounded by a rigid cell wall.

    - Osmotic pressure in plant cell causes cell to swell against the cell wall, but not burst

    = Turgor Pressure

    - gives plants, stems and leaves their rigid, upright form.

Plant cells1
Plant Cells


= loss of turgor pressure in plants

- cell shrinks from cell wall

- less rigid