BIOL 113

Question 1

What is true breeding

Answer 1

when individuals true breed they produce offspring with the same characteristics

Question 2

What does mendels model state

Answer 2

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

Question 3

How do you determine genotype of an individual

Answer 3

You cross it with a homozygous recessive individual (50/50 = heterozygous)

Question 4

What is mendels law of independant assortment?

Answer 4

Each pair of alleles assorts independantly to the oter during gamete formation (dihybrid is example)

Question 5

What is the dyhybrid recombinant ratio?

Answer 5

9:3:3:1

Question 6

How to solve complex genetic problems (more than dihybrid)

Answer 6

Multiply individual probabilities (from individual punnet squares) together to get overall probability

Question 7

What is the law of segregation

Answer 7

the two alleles present in each dipliod segregate independantly

Question 8

How do you determine recombination frequency?

Answer 8

(Number of recombinants/ total number of progeny) x100%

Question 9

How to map chromosone linkage using recombination frequency?

Answer 9

Using two point crosses to find differences.
You can use three point crosses to shortcut it.

Question 10

What is the maximum recombination frequency you can get

Answer 10

50%

Question 11

What is pleiotropy

Answer 11

It is where a single gene has multiple effects on phenotype such as one gene deciding flower and seed colour at once.

Question 12

What is polygenic inheritence?

Answer 12

Where a single phenotype/trait is determined by multiple genes.

Question 13

What are three ways to identify a chromosome?

Answer 13

1) Length
2) Banding pattern
3) Placement of centromere

Question 14

What is karyotyping used for?

Answer 14

To detect changes in chromosome number and structure

Question 15

What does the Hershey-Chase expermient prove?

Answer 15

That DNA is the hereditary component of the T2 phage (as it was inherited in offspring but proteins weren’t)

Question 16

What is the point where DNA replication starts from called?

Answer 16

The origin of replication

Question 17

What protein replaces RNA with DNA in DNA replication?

Answer 17

DNA PolI

Question 18

What protein joins Okazaki fragments (primers joining to lagging strands)

Answer 18

DNA ligase

Question 19

How did beadle and tatum test that genes were responsible for chemical reactions?

Answer 19

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.

Question 20

What is wobble base pairing in tRNA?

Answer 20

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.

Question 21

what catalyses peptide bond formation in tRNA

Answer 21

peptidyl transferase

Question 22

Where does tRNA join to the ribosome?

Answer 22

At the A, P and E binding sites

Question 23

How does UV light damage DNA

Answer 23

It is absorbed by pyramidine bases and can cause adjacent T or C nucleotides to form dimers and join together

Question 24

How are thymine dimers (UV light damaged DNA) removed ?

Answer 24

By nucleotide excision repair (NER)

Question 25

What is cystic fibrosis?

Answer 25

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.

Question 26

What is sickle cell anaemia?

Answer 26

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.

Question 27

What is huntingtons disease?

Answer 27

Late-oneset degeneration of the brain due to a a dominant autosomal mutation.

Question 28

What is familial hypercholesterolaemia?

Answer 28

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)

Question 29

What is Duchenne muscular dystrophy?

Answer 29

A muscle wasting genetic disease caused by a defect on dystrophin (largest human gene which makes gene therapy difficult and untreatable)

Question 30

Why is RNA sequencing used?

Answer 30

to study gene expression and determine gene networks and anything affecting them

Question 31

What does spacial transcriptomics do?

Answer 31

Allows you to get information on where genes are expressed.

Question 32

What is the advantage of using multi-omics rather than single omics?

Answer 32

Looking as single omics you can sometimes miss key information.

Question 33

What is DNA barcoding used for?

Answer 33

Examples: Food fraud detection (horse meat) Pollen identification Pathogen surveillance

Question 34

What is BLAST?

Answer 34

A database search tool for genetic sequencing.

Question 35

What is sequence alinment?

Answer 35

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)

Question 36

Why do we not use google or chatgpt for finding genetic data?

Answer 36

Search engines and ai cannot search through databases yet so you need to search them youself.

Question 37

What types of bacteriophage life cycles are there?

Answer 37

Lytic - multiply and lyse the bacterium Temperate - integrate and remain dormant replicating with bacterial dna

Question 38

How can gene transfer and recombination occur in bacterial strains?

Answer 38

Transformation, transduction and conjucation

Question 39

How does transduction occur?

Answer 39

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.

Question 40

What is conjugation?

Answer 40

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)

Question 41

What is negative and positive regulation in bacterial protein synthesis.

Answer 41

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.

Question 42

Why are eukaryotic genomes generally large?

Answer 42

More complex organisms require more genes to code for the complexity. There is a large ammount of non-coding DNA

Question 43

What is tandemly repetitive (satellite) DNA?

Answer 43

A repeating section of DNA usually found at telomeres and centromeres.

Question 44

Whate is interspersed repetitive DNA

Answer 44

Repeated units scattered throughout the gene that are not necessarily identical but closely related. They make up 25%40 of most mammalian genomes.

Question 45

What types of chromatin are there?

Answer 45

Heterochromatin - highly conndensed during interphase and not transcribed Euchromatin - less condensed during interphase and able to be transcribed.

Question 46

What does DNA methylation and Histone Acetylation do?

Answer 46

Mathylation: Compact structure (inactive DNA) Acetylation: loose structure (easily transcribed)

Question 47

What is the TATA box?

Answer 47

A key part of the promoter region abour 10-35bp before transcription start site. It provies the initial binding point for transcription initiation machinery.

Question 48

What binds to TATA to allow RNA polymerases to bind to promoters

Answer 48

TFIID, TFIIA, TFIIB, TFIIF (double check) after RNA polymerase TFIIE and TFIIH bind as well.

Question 49

What is alternative RNA splicing.

Answer 49

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)

Question 50

What is a gene cascade?

Answer 50

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.

Question 51

Whats the difference between a determined cell and a differentiated cell?

Answer 51

Determined cell has master regulatory gene turned on but not cell-specific genes Differentiated cells have both turned on

Question 52

How is a muscle cell determined and differentiated?

Answer 52

Embryonic precursor cells recieve signals activating myoD master regulatory gene which produces transcription factors and sends transcription factors to activate genes for muscle proteins.

Question 53

What are the main phases of drosophila development?

Answer 53

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)

Question 54

What is bicoid and what happens when it mutates?

Answer 54

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.

Question 55

How are body parts determined by Hox genes?

Answer 55

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.