DNA and proteins

Question 1

The genetic code is:

Answer 1

1. Degenerate - some aa’s specified by more than one codon (each codon specifies one aa) 2. Universal - All living organisms use the same code 3. Non-overlapping - codons do not overlap, each nucleotide is read once

Question 2

Types and functions of RNA

Answer 2

mRNA - printed as long, linear transcript, with a 5’ cap and a 3’ tail rRNA - ribosomal RNA (four types combine with proteins to form 80s ribosomes) tRNA - very small, carries aa’s to ribosomes

Question 3

What are the stages of mitosis (5)

Answer 3

1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase

Question 4

What occurs during prophase?

Answer 4

1. chromatin condenses into chromosomes 2. centrosomes form microtubules and move to opposite poles

Question 5

What occurs during prometaphase?

Answer 5

1. Nuclear membrane breaks down 2. Microtubules enter nuclear space 3. Microtubules attach to chromatids

Question 6

What occurs during metaphase?

Answer 6

1. Chromosomes line up along equator of cell

Question 7

What occurs during anaphase?

Answer 7

1. Microtubules pull sister chromatids to opposite poles of cell

Question 8

What occurs during telophase?

Answer 8

1. Nuclear membrane reforms 2. chromosomes reform chromatin

Question 9

Splicing:

Answer 9

Removal of introns from pre-mRNA to form mRNA

Question 10

Exon shuffling:

Answer 10

Duplication, loss, or reshuffling of exons from pre-mRNA to produce different mRNA sequences from the same gene

Question 11

What are the underlying principles of genetics (mendel)?

Answer 11

1. Segregation 2. Dominance 3. Independent assortment

Question 12

What is segregation (mendel)

Answer 12

For any trait, each parents pairing of alleles split, and the allele passed on to offspring is random

Question 13

What is independent assortment?

Answer 13

Different pairs of alleles are passed onto the offspring independently of each other. Inheritance of genes at one location does not affect other locations.

Question 14

What is genomic imprinting?

Answer 14

An epigenetic phenomenon causing genes to be expressed depending on if it is inherited from mother or father

Question 15

From who is mtDNA inherited?

Answer 15

mitochondrial DNA is all inherited from the mother

Question 16

What are homoplasmy and heteroplasmy?

Answer 16

Homoplasmy - A eukaryotic cell whose copies of mtDNA are all identical Heteroplasmy - Presence of more than one type of mtDNA in an individual

Question 17

What is an autosome?

Answer 17

Any chromosome other than the sex chromosomes that occurs in pairs of diploid cells

Question 18

What is allelic heterogeneity?

Answer 18

A situation in which different mutations in the same gene result in the same clinical condition

Question 19

What is consanguinity

Answer 19

Reproductive union between two relatives (incest)

Question 20

What is autozygosity?

Answer 20

Alleles which are identical (homozygous by descent) as a result of inheritance through consanguinous mating

Question 21

What is mosaicism?

Answer 21

When a person is composed of cells of two genetically different types (e.g. down syndrome)

Question 22

What is the karyotype of a cell?

Answer 22

The number and appearance of chromosomes in the nucleus of a eukaryotic cell

Question 23

Describe nondisjunction:

Answer 23

The failure of homologous chromosome pairs to separate normally in mitosis

Question 24

What forces exist in proteins and help to hold them together?

Answer 24

• Van der Waals forces
• Hydrogen bonds
• Hydrophobic forces
• Ionic bonds
• Disulphide bonds