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
Exopeptidases
Hydrolyses the peptide bonds on the terminal amino acids of the peptide molecule
Facilitated diffusion
The passive movement of molecules across the cell membrane via a specific transmembrane protein
- protein channels, carrier proteins
Herd immunity
The higher % of population that are immunised the fewer people there are to pass on the disease
High water potential
> higher %of water molecules
low % solute
low solute concentration
hypotonic
HIV
Human Immunodeficiency Virrus
> infected TH cells
> immune system becomes weak and develops AIDS
> HIV doesn’t kill you directly, immune system deteriorates
Ileum
Long muscular tube, produces enzymes in glands
Inner walls folded into villi -> microvilli, give large surface area
Ileum structure
Thin walls - reduce diffusion distance
Contain muscle - able to move, maintain concentration gradient
Capillary network - blood carried away has absorbed molecules, maintain concentration gradient
Indirect test for antibodies
1) antigen is fixed to the well
2) a sample is added (complementary = antigen antibody complex)
3) rinse to remove unbound antibodies
4) a different antibody is added with an enzyme attached (only bind if first antibody is present)
5) rinse to remove unbound antibodies + enzyme
6) substrate added, colour change
Large intestine
Absorbs water - most from secretions of the digestive gland
Levels of cell fractionation
Ribosomes (lightest) endoplasmic reticulum Lysosomes Mitochondria Chloroplasts Pellet nuclei (heaviest)
Light microscope
> easy
cheap
colour image
> much longer magnification and resolution
can’t see small organelles
Lipases
Hydrolyses lipids into glycerol and fatty acids
Lipid digestion
Hydrolysed by lipase- hydrolyse the ester bonds found in triglycerides to form fatty acids and monoglycerides
Emulsification increases the surface area for enzyme action
Low water potential
> low % water molecules
higher % solute
higher solute concentration
hypertonic
Magnification
The degree to which an object has been made bigger
Magnification calculation
I
———
A | M
Medical diagnosis, monoclonal antibodies
1) monoclonal antibodies fixed to a plate
2) sample added, if antigen present it forms antigen antibody complex
3) rinsed to remove unbound antigens
4) same monoclonal antibody is added with an enzyme attached
5) rinsed to remove any unbound antibodies
6) observe to look for marker (if enzyme added substrate, colour change
Mitosis
Interphase: DNA + organelles replicates
Prophase: Chromosomes condense, nuclear membrane breaks down, centrioles move to poles
Metaphase: chromosomes line up at the centre, spindle forms and attach to centromeres
Anaphase: centromere splits, chromatids are pulled to opposite poles
Telophase: nuclear membrane reforms, cytokinesis
Mitosis
Cell division to form 2 genetically identical daughter cells
(For growth and repair, 1 division, 2 daughter cells, 4 stages)
Monoclonal antibodies
Identical antibodies made from the same B-cells/ plasma cells
Organ
A group of tissues working together to perform a specific function
Organ system
A group of organs working together to perform a specific function
Osmosis
The passive movement of water molecules form high water potential to low water potential
Pancreas
Produces secretion called pancreatic juice - contains protease, lipase, and amylase
Passive immunity
When you are given antibodies by another organism
> natural: children to mother via breast milk/ placenta
> artificial: given someone else antibodies
Fast protection
Short term
Antibodies are foreign so break them down
no memory cells
No exposure to antigen
Pathogen
An organism that causes disease
Phagocytosis
(First line of defence, general immune response)
1) phagocyte identifies foreign antigen
2) engulfs it into phagocytise vacuole
3) lysosomes fuse with phagocytise vacuole, release lysozyme, hydrolyse pathogen
4) phagocyte presents the antigen on its surface
Physical breakdown
Broken down by teeth and then muscles in the stomach
Plasma cells
Clones of the selected B-cell with complementary antibody to pathogen antigen
Plasma cells (humoral response)
> make monoclonal antibodies (antigen antibody complex with the antigen)
stick pathogens together via agglutination
phagocytise can destroy many pathogens at ones
when infection is over. Plasma cells are saved as memory B cells
Primary response
> first immune response
slow (phagocytosis, t-cells, b-cells, plasma cells)
pathogen multiplies, feel symptoms
after infection you save memory cells
Production and secretion of proteins
1) nucleus contains the gene fo the protein
2) protein synthesis takes place on the ribosomes of the RER
3) protein transported to the Golgi body in a vesicle
4) Golgi body modifies the protein
5) protein is packed into a Golgi vesicle
6) vesicle is transported to the cell surface membrane
7) Exocytosis - vesicle fuses with the membrane
Production of a virus
Attachment proteins bind to complementary receptor proteins on host
Attachment proteins specific to receptor proteins
Viruses inject their genetic material (hijacks the host cells and used hosts organelles to reproduce more viruses)
Prokaryotic cell structure
Loop of DNA Cytoplasm Small ribosomes Cell membrane Cell wall (murein) Capsule (extra protection) Flagella Plasmid
Protease
Hydrolyses proteins into amino acids
Protein channel
- small charged molecules
- allows water soluble molecules to pass through
- it is an aqueous pore
- selective and passive
- if the particular ion is not present the channel will remain closed
- (ion binds with the protein to change its shape in a way that it closes on one side and opens on the other)
Rectum
Stores faeces
Resolution
The shorter distance between two points that can be seen
Salivary gland
Pass secretions via duct into the mouth - contains analyse
Secondary response
> same pathogen infects you
immune response: faster, strong energy, plasma cells, kill pathogen, no symptoms
Memory T-cells (cellular), memory B-cells (humoral)
SEM
> much better magnification and resolution than light
shorter wavelength
3D image
don’t need a thin slice
> longer magnification and resolution than TEM
can’t we internal structures
Size conversion
m x 1000 mm x1000 um x1000 x1000 nm
Specialised cells
Cells have evolved to carry out specific functions
They need different adaptions to do this efficiently
Specialised cells
A cell with an adaption specific to its function
Stages of the immune response
> phagocytosis
T-cells
B- cells
Plasma cells
Stomach
Inner layer contains glands that produce enzymes
T-Cells
(Activated by the antigens presented by phagocyte )
1) t-helper cells (activate B-cells)
2) TC cells (kills pathogens)
Targeting medication, monoclonal antibodies
> monoclonal antibodies can be used to deliver drugs
ALL cells have different/ specific antigens on their surface
monoclonal antibodies can be made to bind to any target cell
attach drugs to antibodies and bond to target cell
drug and antibody will only target cells
TEM
> better magnification and resolution than SEM
shorter wave length than light
allows internal structure to be seen
> can’t look at living cells
specimens need to be in vacuum
need a thin slice (artefacts)
doesn’t form colour image
The structure of an antibody
> they are proteins (specific 1, 3 structure)
antibodies are complementary to antigens and form antigen antibody complex
TOP: variable region (where antigen goes)
BOTTOM: constant region
BOND: disulphides bridges
Tissue
A group of cells working together to perform a specific function
Treatments to cancer
Control/ restrict division
It kills normal cells
Because cancer cells divide more, more cancer cells are killed than normal cells
Vaccine
Contains antigen from a dead/ weakened pathogen
> stimulates the immune system to produce antibodies/ plasma/ memory cells
> if become infected, get secondary response
Virus reproduction
1) virus attachment protein bond to receptor on host
2) reverse transcriptase (make double stranded DNA from RNA
3) DNA enters nucleus via nuclear pore
4) TH cells make more copies of virus genetic material + proteins
5) reforms capsid
6) leaves host cell + takes envelope from host membrane
fix law
rate of diffusion = surface area x difference in concentration/ length of diffusion pathway
stages of active transport
- there are carrier proteins along the plasma membrane and they bind to the molecule/ ion to be transported on one side of it
- they bind to the receptor sites on the carrier proteins
- on the inside ATP binds to the protein, causing it to split to ADP + Pi - this causes the protein molecule to change shape and open on the opposite side of the membrane
- molecule/ ion is released to the other side of the membrane
- phosphate molecule is released from protein causing protein to revert to its original shape
- phosphate recombines with ADP to form ATP during respiration
increasing the rate of movement across ileum membrane
- microvilli
- provide more surface area for the insertion of carrier proteins
- increase transport - increase the number of protein channels and charrier proteins at any areas of a membrane
role of diffusion in absorption in the ileum
- greater concentration of glucose and amino acids within the ileum than the blood
- the blood is constantly moving and the glucose absorbed is constantly being used through respiration
- helps to maintain the concentration gradient between the inside of the ileum and the blood
- rate of facilitated diffusion across the epithelial cell surface membrane increases
role of active transport in absorption of the ileum
- diffusion should results in the concentration being equal - means that not all available glucose and amino acids can be absorbed and some passed through the body
- BUT this doesn’t happen as it is being actively transported
- this means that all glucose and amino acids are absorbed into the blood
