Topic 2 - Cells Flashcards
A cellular
Don’t have their own cells
Absorption of amino acids and monosaccharides
Protein digestion - amino acids
Carbohydrate digestion - galactose, glucose, fructose
Absorbed by diffusion and co transport
Absorption of glucose in the ileum
- sodium ions are actively transported out of the epithelial cells by the sodium potassium pump into the blood (potassium moves in from the blood)
- this maintains a higher concentration of sodium in the lumen of the intestine than in the epithelial cells
- sodium diffuses into the epithelial cells down the concentration gradient through a co transport protein
- as the sodium is diffused through this protein they carry a glucose molecule into the cell
- the glucose passes into the blood plasma by facilitated diffusion using another carrier
- the sodium concentration gradient powers the movement of glucose not ATP
- indirect active transport
Absorption of triglycerides
When in contact with the epithelial cell the micelles break down releasing monoglycerides and fatty acids. When in the epithelial cell they are transported to the ER where they are recombined to form triglycerides
Active immunity
When you make your own antibodies > natural: primary response > artificial: Vaccination slow Long term Make memory cells Exposed to the antigen
Active transport
> against the concentration gradient
using energy from ATP
via a carrier protein (they act as ‘pumps’)
selective process
Antibodies
Proteins that bind to antigens to kill pathogens
Antigens
Proteins on the surface of cells which cause an immune response
Antigentic variability
> antigens on the surface of pathogens change
antigen is no longer complementary to antibody
infected again, primary response
some pathogens have many strains
vaccine will only work on some strains
B-cells
> many types of B-cells, each with own specific antibody
the B-cell with the complementary antibody forms antigen-antibody complex (activates the right B cell)
selected B-cell divides/ clones itself (many = plasma cells)
Binary fission
Asexual reproduction of single celled organisms
Binary fission stages
> how bacteria divide
circular loop of DNA replicates and moves to opposite ends of the cell
plasmids replicate
cytoplasm divides to form two daughter cells, each with a single copy of circular DNA
Cancer
An uncontrolled cell division
Cancer and mitosis
> normally cells divide in a regular and controlled way
mitosis is controlled by genes
if a gene mutates a cell can divide rapidly
cells divide too often and form a tumour
Carbohydrases
Hydrolyses carbohydrates into monosaccharides
Carbohydrate digestion - Amylase
Amylase hydrolyses the glycosidic bonds of starch into the disaccharide maltose
Carbohydrate digestion - lactase
Lactase hydrolyses single glycosidic bonds in lactase producing glucose and galactose
Carbohydrate digestion - maltose
Maltose is hydrolysed by maltase into a glucose
Carbohydrate digestion - sucrase
Sucrase hydrolyses the single glycosidic bonds in sucrose - produces glucose and fructose
Carrier proteins
- large molecules
- molecule that is specific to the protein will bind eg glucose
- it will change shape to the specific molecule to allow it to open to and be released on the inside
Carrier proteins and proteins channels
> high to low concentration
specific. Each molecules has its own transport protein
the same proteins can be used for active transport
Cell fractionation
1) breakers cell open (ice cold, keep isotonic, use buffer)
2) filter solution (removes cell debris and whole cells)
3) ultra centrifugation (spin test tube, heaviest to the bottom, remaining liquid removed, spin again, next heaviest removed in pellet, repeat)
Cell surface membrane
> phospholipid bilayer
hydrophilic heads face outwards
hydrophobic tails face inwards
phospholipids can slide over each other
small non-polar molecules can diffuse through
water is polar so doesn’t diffuse through easily (moves in through aqua proteins)
Cell surface membrane components
Glycoprotein - carbohydrate and protein Cholesterol Channel and carrier protein Glycolipid - carbohydrate and lipid Proteins
Chemical breakdown
Hydrolyses large insoluble molecules into smaller ones, carried out by enzymes
Cholesterol in the cell surface membrane
> binds to hydrophobic tails
makes membrane more rigid
strengthens and supports
Clonal selection
Only the B-cell that forms a antigen-antibody complex is selected to divide into plasma cells
Co transport
> via a carrier protein
moves two molecules at once
one goes down the concentration gradient
the other goes against the concentration gradient
Components of virus
Capsid, genetic material, attachment proteins
Diffusion
Net movement of molecules from high to low concentration
Diffusion - concentration gradient
> steeper the concentration gradient the faster the rate of diffusion
Diffusion, surface area
> the bigger the surface area that faster the rate of diffusion
Diffusion, the distance
> the shorter the diffusion distance the faster the rate of diffusion
Dipeptidases
Hydrolyse the bond between two amino acids of a dipeptide - are membrane bound and are part of the cell surface membrane of the epithelial cells of the ileum
direct test for antigens
1) immobilised antibodies are attached to well
2) sample added
3) if blood plasma contains antigen (antigen antibody complex)
4) rinse to remove unbound antigens
5) antibody + enzyme is added
6) rinse to remove unbound antibodies
7) add substrate, if positive colour change
ELISA
Enzyme Linked Immuno Sorbent Assay
> test to see if patients have a specific antibody or antigen
> antibody with a enzyme attached
Endopeptidases
Hydrolyse the peptide bonds between amino acids in central region of a protein molecule
Eukaryotic cell organelles
Nucleus (chromosomes, makes ribosomes)
RER (modifies and folds proteins, covered in ribosomes)
SER (same as RER, no ribosomes)
Golgi aparatus (modify + package proteins and lipids, make lysosomes)
Golgi vesicle (store and transport proteins and lipids)
Lysosomes (contain digestive enzymes)
Mitochondria (site of aerobic respiration)
Cell Wall (structural support)
Vacuole (cell sap)
Chloroplast (site of photosynthesis)
Ribosome (make proteins)
Eukaryotic cells
Plants, animals, algae, fungi