BIOL 113 Flashcards
What is true breeding
when individuals true breed they produce offspring with the same characteristics
What does mendels model state
1) variation is due to alleles
2) Each parent gives one allele to offspring
3) dominant alleles determine appearance (phenotye)
4) Alleles do not blend
5) alleles segregate during gamete formation
How do you determine genotype of an individual
You cross it with a homozygous recessive individual (50/50 = heterozygous)
What is mendels law of independant assortment?
Each pair of alleles assorts independantly to the oter during gamete formation (dihybrid is example)
What is the dyhybrid recombinant ratio?
9:3:3:1
How to solve complex genetic problems (more than dihybrid)
Multiply individual probabilities (from individual punnet squares) together to get overall probability
What is the law of segregation
the two alleles present in each dipliod segregate independantly
How do you determine recombination frequency?
(Number of recombinants/ total number of progeny) x100%
How to map chromosone linkage using recombination frequency?
Using two point crosses to find differences.
You can use three point crosses to shortcut it.
What is the maximum recombination frequency you can get
50%
What is pleiotropy
It is where a single gene has multiple effects on phenotype such as one gene deciding flower and seed colour at once.
What is polygenic inheritence?
Where a single phenotype/trait is determined by multiple genes.
What are three ways to identify a chromosome?
1) Length
2) Banding pattern
3) Placement of centromere
What is karyotyping used for?
To detect changes in chromosome number and structure
What does the Hershey-Chase expermient prove?
That DNA is the hereditary component of the T2 phage (as it was inherited in offspring but proteins weren’t)
What is the point where DNA replication starts from called?
The origin of replication
What protein replaces RNA with DNA in DNA replication?
DNA PolI
What protein joins Okazaki fragments (primers joining to lagging strands)
DNA ligase
How did beadle and tatum test that genes were responsible for chemical reactions?
They grew neurospora in specific mediums after exposing them to X-rays to determine if the mutations prevented specific reactions required for growth and then added the nutrient they couldn’t synthesise to ensure they were correct.
What is wobble base pairing in tRNA?
There are fewer types of tRNA than there are codons because for codons that code for the same amino acids only the first two bases are important and the last is the wobble poition that can change.
what catalyses peptide bond formation in tRNA
peptidyl transferase
Where does tRNA join to the ribosome?
At the A, P and E binding sites
How does UV light damage DNA
It is absorbed by pyramidine bases and can cause adjacent T or C nucleotides to form dimers and join together
How are thymine dimers (UV light damaged DNA) removed ?
By nucleotide excision repair (NER)
What is cystic fibrosis?
It is a mutation in the CF gene which chodes for a cloride channel and makes it degreade more quickly resulting in overproduction of mucus from secretory epithelial tissue.
What is sickle cell anaemia?
A mutation resulting in a change from hydrophilic to hydrophobic amino acid being used in haemogloin B resulting in incorrect folding and deformation of RBC.
What is huntingtons disease?
Late-oneset degeneration of the brain due to a a dominant autosomal mutation.
What is familial hypercholesterolaemia?
An incomplete dominance mutation in LDL receptor that is responsible for removing cholesterol from blood. (heterozygous lives longer but is still affected whereas homozygous dies very young)
What is Duchenne muscular dystrophy?
A muscle wasting genetic disease caused by a defect on dystrophin (largest human gene which makes gene therapy difficult and untreatable)
Why is RNA sequencing used?
to study gene expression and determine gene networks and anything affecting them
What does spacial transcriptomics do?
Allows you to get information on where genes are expressed.
What is the advantage of using multi-omics rather than single omics?
Looking as single omics you can sometimes miss key information.
What is DNA barcoding used for?
Examples:
Food fraud detection (horse meat)
Pollen identification
Pathogen surveillance
What is BLAST?
A database search tool for genetic sequencing.
What is sequence alinment?
It compares sequences of DNA and shows differences in the sequences and if they effect the amino acids (and how much an amino acid change affects the protein)
Why do we not use google or chatgpt for finding genetic data?
Search engines and ai cannot search through databases yet so you need to search them youself.
What types of bacteriophage life cycles are there?
Lytic - multiply and lyse the bacterium
Temperate - integrate and remain dormant replicating with bacterial dna
How can gene transfer and recombination occur in bacterial strains?
Transformation, transduction and conjucation
How does transduction occur?
Bacterial DNA is hydrolysed when bacteriophage injects viral DNA and occasionally bacterial DNA is packaged in a phage capsid which is injected into another bacterium allowing for crossing over. Or bacterial DNA is picked up alongside the viral DNA and is injected alongside the viral DNA.
What is conjugation?
The transfer of replicate DNA via a sex pilli between two bacteria and is determined by the F factor plasmid.
Either the plasmid is replicated (if seperate) or the whole DNA is replicated until the sex pilli seperates (if plasmid integrated)
What is negative and positive regulation in bacterial protein synthesis.
In negative the protein produced binds to a repressor protein which stops RNA from being produced to produce more protein
In postive the repressor is deactivated by the target protein turning on gene expression.
Why are eukaryotic genomes generally large?
More complex organisms require more genes to code for the complexity.
There is a large ammount of non-coding DNA
What is tandemly repetitive (satellite) DNA?
A repeating section of DNA usually found at telomeres and centromeres.
Whate is interspersed repetitive DNA
Repeated units scattered throughout the gene that are not necessarily identical but closely related.
They make up 25%40 of most mammalian genomes.
What types of chromatin are there?
Heterochromatin - highly conndensed during interphase and not transcribed
Euchromatin - less condensed during interphase and able to be transcribed.
What does DNA methylation and Histone Acetylation do?
Mathylation: Compact structure (inactive DNA)
Acetylation: loose structure (easily transcribed)
What is the TATA box?
A key part of the promoter region abour 10-35bp before transcription start site. It provies the initial binding point for transcription initiation machinery.
What binds to TATA to allow RNA polymerases to bind to promoters
TFIID, TFIIA, TFIIB, TFIIF (double check)
after RNA polymerase TFIIE and TFIIH bind as well.
What is alternative RNA splicing.
The gene can be spliced in different ways to include different exons which can affect the protein produced (such as alpha-tropomyosin coding for most types of muscle such as smooth and striated or Dscam which can generate 30,000 proteins on growing neurons)
What is a gene cascade?
The master regulatory gene is activated by a signal making transcription factors that activate more genes which in turn activate cell-specific genes to differentiate a cell.
Whats the difference between a determined cell and a differentiated cell?
Determined cell has master regulatory gene turned on but not cell-specific genes
Differentiated cells have both turned on
How is a muscle cell determined and differentiated?
Embryonic precursor cells recieve signals activating myoD master regulatory gene which produces transcription factors and sends transcription factors to activate genes for muscle proteins.
What are the main phases of drosophila development?
1) Establishing main axes (which direction is front and which is back ect
2) Establishing segments (3 head, 3 thorax, 9 abdomen)
3) Filling in the details (finalises development of segments into organs)
What is bicoid and what happens when it mutates?
Bicoid is a gene that codes for a protein that spreads in a gradient from one end of the cell to another determining which end is anterior by the concentration of bicoid.
When the maternal gene is defective creating a gradient of morphogens (transcription factors) which initiate a gene cascade resulting in two posterior regions.
How are body parts determined by Hox genes?
Hox genes encode transcription factors with a conserved DNA binding domain. They occur in clusters that are arranged in the same order as their effected regions (e.g head first in the gene and tail at the end of the gene)
These genes are present in both flies and mammals which suggests they played important evolutionary roles.
