DNA, genes and protein synthesis

Question 1

What is a gene

Answer 1

A section of DNA that contains the coded information for making polypeptides and functional RNA. It is located on the LOCUS of a DNA molecule.

Question 2

What does a gene code for

Answer 2

-amino acid sequence of a polypeptide
- functional RNA, including ribosomal RNA and transfer RNAs.
One DNA molecule carries many genes

Question 3

Features of the genetic code

Answer 3

• Degenerate- a few amino acids are coded for by only a single triplet, the remaining amino acids are coded for by between 2 and 6 triplets each. Most amino acids are coded for by more than one triplet
  -Non overlapping. A triplet is always read in one particular direction along the DNA strand. It starts with methionine (the starting triplet) that is later removed from the polypeptide chain. Base sequence is only read once
  -Universal. Each triplet codes for the same amino acid in all organisms. This is indirect evidence for evolution.

Question 4

Extrons VS introns

Answer 4

Much of DNA in eukaryotes doesnt code for polypeptides. Between genes there are non-coding sequences made up of multiple repeats of base sequences. Even within genes only certain sequences code for amino acids. Coding sequences are called extrons. Extrons are seperated within the gene by further non-coding sequences called introns. Some genes code for ribosomal RNA and transfer RNAs

Question 5

Homologous chromosome

Answer 5

Two chromosomes that carry the same gene but not necessarily the same alleles of the gene

Question 6

Allele

Answer 6

Alternative form of a gene. Each individual inherits one allele from each of its parents

Question 7

Prokaryotic VS eukaryotic DNA

Answer 7

Prokaryotic and mitrcondrial/ chlorplast DNA= short, circular, not associated with histones
Eukaryotic= long, linear and associated with histones

Question 8

locus

Answer 8

location/position of a gene on a chromosone