Chapter 1 Meneely

Question 1

Mendel’s rule of segregation

Answer 1

A heterozygote has a different allele on each homolog

Replication at S phase produces two sister chromatids

The homologs pair and synapse during Prophase I

Homologs separate during Anaphase I

Question 2

Mendel’s rule of independent assortment

Answer 2

Orientation A at Metaphase I

Segregation at Anaphase I

Completing Meiosis II

Question 3

Linkage and crossing over

Answer 3

No crossing over
25% 25% 25% 25%

vs

Crossing over (btw B & C)
<25%
<25%
>25%
>25%

Question 4

Alleles for a gene

Answer 4

Multiple Alleles for a gene:
Insertions
Deletions of exons and introns (introns spliced)
Amino acid change

Question 5

Gene interactions

Answer 5

Wildtype
Mutant
Suppression
Enhancement

Question 6

One gene, one protein

Answer 6

Genes affecting biosynthesis
(Arg 4, Arg 2, and Arg 1)
essentially producing a biochemical pathway

Arg4 –> enzyme A –> enzyme A catalyses reaction

Arg2 –> enzyme B –> enzyme B catalyses reaction

Arg1 –> enzyme C –> enzyme C catalyses reaction

Question 7

The central dogma of molecular biology

Answer 7

DNA —transcription—> RNA —translation—> polypeptide

Question 8

The collinearity of genes, transcript, and polypeptides

Answer 8

The number of nucleotides can indicate the percentage of similarity among organisms.

Question 9

Transcripts and genes:
rRNA and tRNA genes

Answer 9

Ribosomal RNA (rRNA) and transfer RNA (tRNA) genes:
- Produce stable RNA products
- are clustered in the genome
- are transcribed by RNA POI I or RNAPol III
- are transcribed in all cells

Question 10

Transcripts and genes:
Protein-coding (mRNA) genes

Answer 10

• Produce unstable RNA products
• are scattered throughout the genome
• are transcribed by RNA pol II
• have characteristic expression profiles
• have transcripts that vary in length (average is ~4.5kb)
• encode an amino acid sequence

Question 11

Transcripts and genes:
Micro RNA genes

Answer 11

• produce unstable RNA products
• are scattered throughout the genome
• are transcribed by RNA Pol II
• have characteristic expression profiles
• have transcripts that are 22nt in length
• do not encode an amino acid sequence

Question 12

Role of dsRNA in interactions between miRNAs and their target mRNAs

Answer 12

The dsRNA blocks translation of the mRNA or targets mRNA for degradation

Question 13

Transcripts and genes:
Long non-coding (Inc) RNA genes

Answer 13

• produce stable or unstable RNA products
• are scattered throughout the genome
• are transcribed by RNA Pol II
• have characteristic and cell specific expression profiles
• are often present in few copies per cell
• have transcripts of at least 200nt in length
• do not encode an amino acid sequence

Question 14

Complicated biological questions

Answer 14

Phototaxis: why do wild-type flies but not mutant fly attract to UV-light?

Question 15

Phototaxis requires:

Answer 15

Light receptors in the eye pass a signal to the brain where the signal is processed as an attachment

Impulse are sent from the brain to the wing muscles, which result in wing movement and flight

Question 16

Period gene and emergence

Answer 16

Genetic basis of biological clock
- Mutants that lack functional period are arrhythmic

Period (per) was the first clock gene discovered based on a mutation in emergence patterns

Period was so named due to other alleles that produced emergence rhythm with periods either shorter or longer than 24 hours