Bio paper 1 Flashcards
(24 cards)
describe complete digestion of starch by a mammal.
Hydrolysis of glycosidic bonds.
Amylase converts starch to maltose.
Membrane bound maltase converts maltose into glucose.
compare and contrast the structures of starch and cellulose.
SAME:
- Both polysaccharides
- Both contain glycosidic bonds between monomers
- Both contain C, H & O
DIFF:
- Starch is alpha glucose whereas cellulose beta glucose
- Starch helical whereas cellulose straight
- Starch branched whereas cellulose straight
- cellulose has microfibrils whereas starch doesn’t
describe the transport of carbohydrates in plants
Sucrose actively transported into phloem cell by companion cells
This lowers the water potential of phloem so water enters from xylem via osmosis
Produces hydrostatic pressure gradient causing mass flow to respiring cells
Sucrose unloaded from phloem by active transport.
describe viral replication
Attachment proteins bind to receptors on membrane of host cell
Viral nucleic acid enters cell
Reverse transcriptase makes DNA from RNA
Cell produces viral proteins
Viral proteins assemble at cell membrane
Virus ‘buds off’ and is released from cell
describe the structure and function of the nucleus
- Nuclear envelope and pores
- Chromosomes
- Dense nucleolus
- Holds genetic information
- DNA replication
- Production of mRNA
- Production of ribosomes
describe the role of a ribosome in the production of a polypeptide (don’t include transcription)
- mRNA binds to ribosomes
- mRNA has 2 codons
- Complementary tRNA anticodons bind to the mRNA codons
- This catalyses the formation of a peptide bond between amino acids on tRNA molecules
- Ribosome moves along mRNA to next codon
High absorbance of salt from diet can result in higher than normal conc. of salt in blood plasma entering capillaries which can lead to build up of tissue fluid.
How?
Higher salt = lower water potential of tissue fluid
This means less water is returned to the capillary by osmosis at the venule end.
Suggest an advantage to a bacterium of secreting extracellular protease in its natural environment.
Allows them to digest proteins.
This means they can absorb amino acids for growth
describe how presentation of a virus antigen leads to secretion of an antibody against this viruses antigen
Helper T cell binds to the antigen on antigen-presenting cells
This helper T cell stimulates a specific B cell
B cell divides by mitosis forming clones
B cell forms plasma cells which secrete antibodies
How do enzyme-substrate complexes increase the rate of reaction
Reduce activation energy due to bending bonds
Without enzymes, very few substrates have sufficient energy for reaction
Formation of lactose and where in the cell would it be attached to a polypeptide to form a glycoprotein
Condensation reaction between glucose and galactose joined by a glycosidic bond.
Added to polypeptide in glogi apparatus
Why does the binding of 1 molecule of oxygen to Hb makes it easier for 2nd to bind
Binding of the 1st oxygen molecule changes the tertiary structure of the Hb
This uncovers a second binding site on the Hb for te 2nd oxygen to bind to
Name the two scientists who proposed models of chemical structure of DNA and DNA replication
Watson and Crick
Outline the cellular response
Complementary T helper cells bind to foreign antigens on antigen presenting cells
They release cytokines which stimulate:
- Conal expansion of complementary T helper cells which can either become memory cells or trigger the humoral response
- Clonal expansion of cytotoxic T cells which secrete perforin enzyme which destroys infected cells
Outline the humoral response
- Complementary T helper cells bind to foreign antigens on antigen presenting T cells
- Cytokines are released which stimulate clonal expansion of complementary B lymphocytes
- The B lymphocytes differentiate into plasma cells or memory B cells
- Memory B cells store info incase future infection
- Plasma cells secrete antibodies with complemetary variable regions to antigen therefore destroy the antigen
How does the structure of phosphlipids relate to their properties
- Polar so can form a bilayer
- Can form glycolipids by combining with carbohydrates in the cell surface membrane (cell recognition)
Explain properties of water and importance to organisms
- Metabolite so hydrolysis and condensation reactions can occur
- Solvent so that metabolic reactions can occur
- High specific heat capacity so can buffer changes in temperature
- High latent heat capacity so provides cooling effect by evaporation
- Cohesion so supports column of water in plants
- Cohesion so creates surface tension supporting small organisms
species richness
no. of diff species that are living in one community
advantages and disadvantages to famers of replanting hedges
+:
- Greater biodiversity so increase in predators of pests
- Increase in pollinators so higher yield
- Increase in predators of pests so less need for pesticides
-:
- Reduce land area for crop growth
- Increase pest population so less yield
- Greater biodiversity so increase pest population
structure HIV
- RNA genetic material
- Reverse transcriptase
- Protein capsid
- Phospholipid viral envelope
- Attachment proteins
Role of micelles in absorbption of fats into cells lining the ileum
- Micelles include bile salts and fatty acids
- Make fatty acids more soluble in water
- Bring the fatty acids to the lining of the ileum
- Maintain higher conc. of fatty acids to cells of the ileum
- Fatty acids absorbed by diffusion
how and why is there a small increase in pressure and rate of blood flow in the aorta
- elastic recoil of aorta walls
- maintains rate of blood flow
how would anti-toxin antibodies be digested
- Peptide bond hydrolysed
- Endopeptidases break the internal peptide bonds
- Exopeptidases break terminal peptide bonds
- Membrane bbound dipeptidases break dipeptides into amino acids
Lipid digestion
- Bile salts bind to large lipid droplets and emulsify them into smaller droplets creating a large SA for lipases to work on
- Lipase enzymes in the lumen of the small intestine break down lipids to glycerol, monoglycerides and fatty acids
- Monoglycerides and fatty acids associate with bile salts = micelles
- Contents of micelles is non-polar so can diffuse across phospholipid bilayer
- Fatty acids are broken into smaller more soluble molecules
- Short fatty acid chains within the epithelial cells can move directly into the blood via diffusion
- Longer fatty acid chains recombine with monoglycerides and glycerol to form triglycerides in the endoplasmic reticulum
- The triglycerides are packaged into chylomicrons which eventually enter the bloodstream
