week 1

Question 1

what are chromosomes

Answer 1

• made up of DNA wrapped around proteins
  -DNA molecule is highly condensed

Question 2

what is a karyotype

Answer 2

• a description of its compliment of chromosomes, number, size, shape and banding patterns

Question 3

describe DNA replication

Answer 3

• always replicated in the 5’ to 3’ direction
• 5’ triphosphate can only be added to a free 3’ OH on the deoxyribose molecule
• carried out by DNA polymerases
• requires single-stranded DNA template and a double-stranded section with a free 3’ end

Question 4

the central dogma of molecular biology

Answer 4

• transcription of sequence from DNA to RNA then translation to protein

Question 5

differences between DNA and RNA

Answer 5

• in RNA, uracil instead of thymine
• ribose vs deoxyribose
• RNA usually single-stranded vs double-stranded DNA

Question 6

describe protein structure

Answer 6

• they have different levels of structure
• determined by amino acid sequence, the addition of other chemical groups e.g. sugars and the presence of other proteins that aid folding
• proteins determine: cell structure, cell function, metabolism, housekeeping, import/export, signalling etc.

Question 7

describe transcription

Answer 7

• synthesis of mRNA from a DNA template
• requires DNA dependent RNA polymerase enzyme plus four nucleotides (ATP, GTP, CTP and UTP)
• nucleotides not deoxy-nucleotides are used. uracil replaces thymine

Question 8

describe translation

Answer 8

• following the AUG translation initiation signal, discrete codons are read on the mRNA molecule in strict order
• the growing amino acid chain is terminated when any of the 3 stop codons are encountered (UAA, UAG, UGA). translation occurs on ribosomes that are found in the cytoplasm
  -the molecule that matches particular codons to particular amino acids is tRNA
• ribosomes also contain RNA molecules

Question 9

introns vs exons

Answer 9

• in eukaryotes the coding region of a gene is often broken up by introns
• these introns are removed in the nucleus when mRNA is processed
• only exons code for proteins
  -prokaryotic genes don’t usually have introns

Question 10

mitochondrial DNA

Answer 10

• the mitochondrial DNA, unlike nuclear DNA doesn’t associate with histones or other proteins and is circular
• mitochondrial DNA is very gene-rich and contains very little ‘junk DNA’
• mitochondrial DNA has a higher mutation rate than nuclear DNA

Question 11

mitochondrial DNA inheritance

Answer 11

• found in males and females
• because sperm doesn’t contribute its mitochondria to the fertilised egg we only inherit our mother’s mitochondrial DNA
• can be used to investigate female-specific migration history

Question 12

natural events which alter or rearrange DNA sequences

Answer 12

• mutations (point mutation, deletions, rearrangements)
• viral infection
• bacterial infection
• transposons, insertion sequences
• DNA uptake and recombination
• meiosis (sex)

Question 13

what does recombinant DNA technology allow you to do

Answer 13

• isolate a specific gene
• amplify to manageable amounts
• ‘immortalise’ by cloning (plasmids etc)
• read DNA sequence
• manipulate (make specific changes, join to other DNA sequences)
• insert into another organism