PPQ Corrections 3 Flashcards
Transmembrane proteins carry a signal sequence, which halts translation and directs the ribosome synthesising the protein to dock with the…
Endoplasmic Reticulum.
Order of the cell cycle
G1-S-G2-M
What is checked by the G1 checkpoint?
There is enough cell mass for daughter cells.
If there is any DNA damage.
Role of Rb in G1
Tumour suppressor.
Inhibits transcription of genes that code for proteins needed for DNA replication.
Role of G1 Cyclin-CDK
Inhibits Rb by phosphorylation.
Allows transcription of genes that code for proteins needed for DNA replication.
If this happens the cell can progress to S phase.
What happens during the S stage of the cell cycle?
DNA replication.
What happens during the G1 checkpoint if there is DNA damage?
Damage triggers the activation of p53.
Role of p53 in the cell cycle (3).
If activated it can:
- Stimulate DNA repair
- Halt cell cycle
- Cause programmed cell death
G2 checkpoint
Success of DNA replication is assessed.
M checkpoint
Controls progression from Metaphase to Anaphase.
Progression is halted until:
- Chromosomes are aligned correctly on the metaphase plate.
- Spindle fibres are attached.
Meiosis I (5)
- Chromosomes replicate forming two identical chromatids.
- Homologous chromosomes pair up and points of contact form between non-sister chromatids.
- Crossing over takes place.
- Chromosomes attach to spindle fibres and are separated to opposite poles.
- Cytokinesis occurs forming two daughter cells.
Whatis the purpose of crossing over?(2)
Creates new combinations of alleles.
Increases variation.
Meiosis II
Sister chromatids are separated.
Chromosomes segregate into one of the four new haploid cells.
Suggest how you could determine if someone had a parasite?
Through a sample of urine or faeces.
Types of chemical label:
Colour change
Fluorescence
Describe how SDS‑PAGE separates proteins.
All proteins are given a negative charge and are denatured.
Small proteins migrate faster than larger proteins.
What must happen after electrophoresis before Western blotting can be done?
Transfer to a solid medium.
Why is it unethical to only use homeopathic remedies?
There is no evidence that homeopathic remedies work.
The patient may be at higher risk.
2 aspects that cause low reliability are:
Small sample size.
No independent replicate.
During glucose symport what molecule travels with glucose at the same time?
Sodium ions.
How does the sodium potassium pump supply energy for glucose symport?
Sodium potassium pump hydrolyses ATP.
Describe how facilitated diffusion takes place.
Passive transport occurs down a concentration gradient through channels or transporters.
Facilitated diffusion in specific transporters.
Substance binds to transmembrane protein causing a conformational change.
Facilitated diffusion in non-specific channels.
Substance diffuses across pores in channels.
What would a loss of GLUT2 cause?
Glucose would not be able to diffuse out of the liver.
External death signal examples (2).
Binding of lymphocytes.
Absence of growth factors.
Name the enzyme that causes the destruction of cells
during apoptosis.
Caspases
Apoptosis is essential for…(3)
Organism development.
Metamorphosis.
Removing damaged cells.
Virus structure (2)
Contains DNA packaged in a protein coat.
Some viruses are surrounded by a phospholipid membrane which is derived from the host cell.
How are viruses parasitic? (2)
It is a symbiotic interaction where the virus benefits at the hosts expense.
Virus can only replicate inside a host cell.
Retrovirus (2)
Viruses that use the enzyme reverse transcriptase to form DNA from RNA.
This DNA is then injected into the genome of the host cell.
What is a sequential hermaphrodite.
They can have male or and female reproductive organs, but not at the same time.
What is the benefit of a social hierarchy?
Reduces competition.
Most successful alleles passed on.
List 3 costs of external fertilisation.
Gametes are predated.
Low chance of fertilisation.
Few offspring survive.
Name the process that allows genes to move from bacteria and fungi into other species.
Horizontal gene transfer.
Why is parthenogenesis more common in cooler climates?
There is a lower parasite diversity.
Less need for variation by sexual reproduction to combat parasites.
Interspecific competition
Competition that brings about a change in the realised niche of one of the species.
Competitive exclusion
When one species goes extinct in the presence of another.
Response to light in the rod cells of animals. (5)
- Photon of light activates rhodopsin.
- Rhodopsin activates transducin.
- Transducin activates PDE.
- PDE breaks down cGMP.
- Function of channel protein is affected.
Bacteria model organism
E.coli
Nematode model organism
Caenorhabditis elegans
(roundworm)
Chordate model organism
Mice/rats
Arthropod model organism
Drosophila melanogaster
(fruit fly)
Flowering plant model organism
Arabidopsis thaliana
Methods to determine number of viable cells (2)
Vital stain
Colony count
What is a prosthetic group
A non-protein group that is essential for function.
Cooperativity in haemoglobin.
Binding of oxygen at one site affects the binding of oxygen at other sites.
How does increasing negative modulator concentration help oxygen delivery to tissue.
Affinity for oxygen is reduced making it easier for haemoglobin to release oxygen.
Electrochemical gradient
Combination of the concentration gradient and
the electrical gradient.
Why would a positive ion move against its conc. gradient into a negatively charged cell?
Because the effect of the electrical potential difference is greater than that of the concentration gradient.
Steroid hormones diffuse across the membrane and bind to a ________ _____________ receptor.
specific intracellular
HRE’s are
Target DNA sequences
How do steroid hormones affect transcription?
One hormone affects the transcription of many genes.
Action of neurotransmitters (3)
- Neurotransmitters bind to ligand gated channels.
- Sodium channel opens allowing an influx of sodium into the cell.
- If enough sodium ions flow into the cell then a threshold is reached which triggers an opening of more sodium channels resulting in further depolarisation.
How do tumour cell lines differ from primary cell lines?
Tumor cell lines divide indefinitely.
Advantage of using lab animals.
Can see the effect on the whole organism.
How would inhibiting Rb affect cell division?
The cell will progress to S phase without being checked at G1.
What is present in the supernatant
Insoluble substances.
Heritable evidence that may be used to construct a phylogenetic tree.
DNA sequences
What is morphology.
Structure of an organism.
Parthenogenesis
Reproduction from unfertilised eggs.
Benefits of increased variation due to sexual reproduction (3).
Being able to adapt to:
Changing environment.
Increasing temperatures.
Increase in parasitism.
How can a parasite create a new niche for it’s host.
Change in host behaviour can result in a change in resources and competition.
Population size=
MC/R
M= Sample captured and marked.
C= Second sample captured.
R= No. of marked individuals recaptured.
What does an absolute fitness of 1> indicate?
Decrease in frequency.
Symbiotic relationship
A close relationship between 2 species.
Why do many marine life use external fertilisation?
Water allows sperm to reach eggs.
What is a monoclonal antibody?
An antibody derived from a cell line.
Explain why it is important to control pH in immunoassays (2).
pH affects the structure of proteins.
This reduces the affinity of antibodies binding to antigens.
Light sensitive molecule in animals.
Retinal
How do rod cells function in low light?
High degree of amplification.
Epidemiology
Study of the outbreak and spread of diseases.
What effect does selection bias have on the sample?
The sample is not representative.
Why can observational studies only suggest a possible link over time?
Observational studies cannot show causation.
What is an ethogram and what does it measure?
List of behaviours.
Measures:
- Latency (how quickly animals respond to stimulus)
- Duration
- Frequency
AVOID ANTHROPOMORPHISM
How does modification of host behaviour benefit the parasite?
It can allow for the transmission of the parasite.
Examples of behaviour that is altered as part of the extended phenotype of the parasite (3).
Sexual behaviour.
Habitat choice.
Anti-predator behaviour.
Describe monogamy
When females and males only mate with one partner.
Non-specific immune responses (3)
Inflammatory response.
Apoptosis.
Phagocytosis.
What is the term used to describe the difference in size between males and females.
Sexual dimorphism
Causes of sex change in organisms (3)
Dominant male/female dies.
Competition
Parasitic infection.
Examples of hydrophilic signalling molecules (2):
Neurotransmitters
Protein hormones
Signal transduction (3)
- Molecule binds to SPECIFIC receptor (transmembrane protein) on cell membrane.
- This causes a conformational change.
- Cellular response is triggered.
Signal transduction outcomes (2).
Phosphorylation.
Activate G-proteins.
How does the sodium potassium pump work? (8)
- Pump has a high affinity for sodium ions.
- 3 Na+ ions bind to pump.
- The pump is phosphorylated by splitting ATP.
- Conformational change is triggered and affinity for Na+ decreases, releasing sodium out of the cell.
- The pump has a high affinity for Potassium outside of the cell.
- 2 potassium ions bind to the pump.
- The pump is dephosphorylated and returns to its original conformation.
- Potassium is released into cell.
Schistosomiasis in humans is caused by an…
endoparasitic platyhelminth (flatworm)
What is a vector?
An organism that spreads a parasite from one host to another.
Describe the action of caspases in cell destruction. (2)
Break down proteins.
Activate other caspases.
Why do steroid hormones have different effects in different types of tissue? (2)
Different tissues have different responses to receptor binding.
Different genes are switched on/off.
Name the enzyme that dephosphorylates proteins.
Phosphatase
Why is it important that proteins return to their inactive state.
So that the protein can respond again.
How does protein electrophoresis separate proteins.
A current separates proteins by size and charge.
Latency
Viruses escape immune surveillance by integrating their genome into the host genome.
Why are carrier females usually unaffected even though they carry a mutated gene.
X chromosome inactivation is random.
Half the cells will have a functional copy of the gene.
How to construct a time budget.
Calculate duration of each behaviour.
Then calculate proportion of time spent doing each behaviour.
Why should anthropomorphic statements be avoided.
Applying human emotions to animal behaviour can result in misinterpretation of behaviour.
What is the process associated with the red queen hypothesis. (2)
Co-evolution.
When the changes in traits of one species acts as a selection pressure on the other.
Horizontal gene transfer
Transfer of genetic material from one bacterium to another without reproduction.
What does serum provide to cells?
Growth factors
What can be viewed through a bright field microscopy (3).
Tissue
Whole organisms
Parts of organism
Structure of spindle fibres.
Made of microtubules which are composed of tubulin.
Where do spindle fibres radiate from?
The MTOC where they were made.
What does the sodium potassium pump create?
An ion gradient.
Independent assortment
Ensures haploid gametes contain a mixture of chromosomes of maternal and paternal origin.
How to tell if natural selection has taken place.
Organisms have new traits that make them better adapted to a new environment.
What can rapidly increase the rate of evolution? (2)
HIGH selection pressures.
Shorter generation time.
Honest signals
Characteristicsthat indicate a healthy individual with favourable alleles.
What is a lek?
Where males gather to display in order to allow female choice.
Why are displays used as examples of sexual selection?
Display increases chances of passing on genes.
Benefit of honest signals.
Offspring will have more favourable characteristics.
The fundamental niche of a species:
The set of resources available in the absence of competitors.
Intermediate host
A host used by a parasite to multiply asexually.
Why is X chromosome inactivation necessary?
Prevents a double-dose of gene products.
How is X chromosome inactivation expressed in the phenotype? (2)
Only the allele on the active X chromosome is expressed.
Sometimes as cells multiply patches of the dominant and recessive phenotype occur.
Heterogametic
Dissimilar sex chromosomes.
e.g. in mammals X chromosome is larger than Y chromosomes resulting in two types of games.
Homogametic
Sex chromosomes do not differ in morphology resulting in only one type of gamete.
Suggest one way in which greater parental investment is demonstrated.
Greater energy expenditure in care of young.
What happens when CDK’s are activated by cyclins?
Form cyclin-CDK’s which cause the phosphorylation of proteins, which stimulates the cell cycle.
What do cyclin proteins do?
Control the progression of the cell cycle by activating CDK’s.
What do death signal molecules do?
Cause the activation of caspases resulting in apoptosis.
Phylogenetics
The study of the evolutionary history of organisms.
What information does scat sampling tell us? (2)
Abundance
Diet
Commensalism
A symbiotic relationship which is (+/0)
Founder effect (2)
When the gene pool of the new population is not representative of the original gene pool.
Caused by isolation of a few members of a large population.
Relative fitness
No.of surviving offspring of a genotype / No. of surviving offspring of most successful genotype
Homologous chromosomes have the same…
Size and centromere position.
SRY gene
Gene on Y chromosome that determines the development of a male by expressing TDF protein.
Vegetative cloning
Any type of asexual reproduction in plants.
Polyandry
One female mates with many males.
Polygyny
One males mates with many females.
Sexual selection
Selection of characteristics that have little survival benefit but increase chances of mating.
Ectoparasite
Lives on surface of host
Endoparasite
Lives inside of host
Gametocytes
Precursors of male and female gametes.
