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
= The study of cells
= the structural and functional unit of all living things.
= “tiny organ”
= carry out the life
processes of the cell.
* each organelle
has a specific function.
- 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
- A = T
- C = G
= 46 chromosomes in the average human cell
= 23 in the gametes
= sex cells
- dark area of nucleus
- contains rRNA (ribosomal)
= makes 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.
- 2 types;
1. RER = Rough ER
- has ribosomes attached
- helps make proteins
2. SER = Smooth ER
- no ribosomes attached
- sends proteins out from ER
- flattened stacks of membranes in the cell
- modifies, packages, then ships proteins out of the cell in a vesicle
- “power house” of the cell
- supplies energy to the cell (ATP)
- breaks down food to form ATP in a process called Cellular Respiration
- digests/break-down wastes in the cell.
- aid in cell reproduction
- gives support/shape to the
- protective barrier around the cell.
- double layer made up of phosphates and lipids
- controls what enters and exits the cell
- produce sugar in plants
- contain chlorophyll
= green pigment that captures sunlight as energy for plants
- contain red, orange, yellow pigments that give flowers and fruits their color.
- colorless plastid
- convert sugar to starch
- better energy storage form
- 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)
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.
- 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)
Permeability of an object depends on:
1. Size – (sugar/starch)
2. Charge – (+) or (-)
3. Solubility – ability to be dissolved in water
= movement of MOLECULES from an area of high concentration to an area of low concentration.
ex; - sugar in tea
- tea bags
= 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.
- increase the rate of diffusion by using carrier proteins in the cell membrane.
= rate of molecules leaving the cell is = to the rate of molecules entering the cell.
3 types of solutions are possible when compared to the cell.
= number of solutes in fluid is = to the number of solutes in cell
= solution contains a higher number of solutes than the cell
- solutes move into cell, water moves out
- results in cell shriveling
= 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.
- movement of molecules into or out of the cell using cellular energy (ATP)
1. Carrier Mediated Active Transport
- use of carrier proteins (like FD)
- movement from low concentration to high, and uses energy.
- transporting substances into the cell
- membrane surrounds molecule, forms vesicle and pinches off into cell.
- for larger particles
- cell surrounds and engulfs molecule
- 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.
= loss of turgor pressure in plants
- cell shrinks from cell wall
- less rigid