Cells and cell transport Flashcards
Cell membrane
Made of lipids an proteins
Regulates movement of substances into and out of the cell
Contains receptor cells that respond to hormones
Nucleus
Large organelle that contains Chromosomes
Controls cell activity by controlling dna
Makes ribosomes
Mitochondrion
Have a double membrane;
- inner membrane folded to form cristae which contains enzymes involved in respiration
It role is to aerobically respire to produce ATP
Contains matrix - specialised cytoplasm,
And contains the other mitochondrial space
Chloroplasts
- plants only
Where photosynthesis takes place
Thick fluid called stroma containing ; -granum ( layers of thylakoids ) with dots fo chlorophyll on grana - starch grains - 70s ribosomes Surrounded by a double membrane
The Golgi apparatus
Group of fluid filled sacs bound by membranes of which vesicles can often be seen on the surface
Packages new lipids and proteins into vesicles
Makes lysosomes
The vesicles
Stores the lipids and proteins form the Golgi apparatus and transports them out of the cell through the endoplasmic reticulum and cell membrane
Lysosomes
Round organelles
Contain digestive enzymes (lysozyme) that help break down invading cells and worn out components
RER - rough endoplasmic reticulum
Covered in ribosomes
Folds and processes proteins that been made by the ribosomes
SER- smooth endoplasmic reticulum
No ribosomes
Synthesises and processes lipids
The cell wall
- plants only
Rigid structure made of cellulose
Supports the cell
Stops to from changing shape
Vacuole
- plant only
Contains cell sap
Maintains pressure in the cell
Keeps cell rigid
Isolates unwanted chemicals
Prokaryotic cells contain
Flagellum- locomotion
70s ribosomes - proteinsynthesis
Cell wall- protects cell
Capsule- protection from acidic environments
Plasmid - contains useful genes
Bacterial chromosomes - contains vital genes
Mesosome- helps to carry out cellular respiration by inc SA
How do ribosomes differ
Eukaryotes - 80s
Prokaryotes - 70s
Ribosomes
Produced by the nucleus and are made up of RNA
Mains site of proteinsynthesis
Bacterial diseases
Cholera
TB
Meningitis
How bacteria “eat”
Detect the food they are on
Specific genes create specific enzymes to hydrolyse the food
Absorb the broken down food and assimilate
How bacteria exchange genetic info
Through cytoplasmic thread that connects 2 bacterium
Conjugate by sharing plasmids
Virus’ are
X50 smaller than bacteria
Not living
Virus’ are made of
Either DNA or RNA ( RNA = retrovirus )
Protein coat - capsid
Have a lipid and protein envelope containing attachment proteins for identification
Reproduction of a virus
- If the attachment proteins on the virus are complementary to the cell surface proteins the virus will attach and enter the cell
- The membrane and protein coat of the virus disintegrate and the DNA/RNA enters the nucleus of the cell
- If a retrovirus; reverse transcriptase will turn RNA to DNA
- This dna is then copied using specific enzymes
- Viral proteins are made form the copied DNA using the cells ribosomes
- The new virus’ Burst out of the cell and kill the cell in the cell in the process
Fluid mosaic model
-membrane
- proteins and protein pores in a phospholipid bilayer
- H2O, CO2, O2 pass freely across membrane
- alcohol, vit D, steroid hormones are lipid soluble so can pass across bilayer
- Na+, Cl- ions, glucose, amino acids are water soluble so can only enter through specific proteins
- proteins and starch are too big to pass through
What do the proteins in the membranes act as
Hydrophilic pores
Specific receptor sites for hormones
Enzymes
Recognition molecules
Diffusion
The net movement of particles from a region of high conc to a region of low conc until equilibrium is met
Ficks law
Rate of diffusion is proportional to…
(SA x con gradient)/ diffusion distance
Facilitated diffusion
Diffusion ( don conc gradient ) sped up by specific membrane proteins and therefore requires ATP
Steps of FD
- Pore opens in the membrane
- Glucose binds to glucose binding site
- The transporter protein changes shape and transferred the glucose to the other side
Osmosis
The net movement of water particles from a region oh hit water potential to a region of low water potential across a semi permeable membrane until equilibrium is met
Cell in Hypertonic solution
Solution has a More negative W.P.
Cell loses water and shrivels
Cell in isotonic solution
Cell and solution have same W.P.
No osmosis
Cell in hypotonic solution
Solution has a less negative water potential
Cell absorbs water
Swells and bursts
Active transport
The movement of ions or molecules agains a concentration gradient
Using specific membrane proteins and ATP
Steps of active transport
-Glucose from gut to blood
- Na+/ K+ pump uses ATP to move ions into the cell from the gut and then into the blood ( 3Na+ out 2K+ in )
- This creates a region of low conc of Na+ in the cell
- Na+ moves from the gut into the cell via facilitated diffusion. The protein that moves it into the cell also transports glucose
- Therefore there is now a high conc of glucose in the cell so it is moved into the blood via facilitated diffusion
