DNA

• what is a gene

  a base sequence of DNA that codes for a polypeptide or functional RNA
• what is a locus

  the position of a gene on a chromosome
• what is an intron

  a non coding sequence that is found within a gene
• what is an exon

  a sequence of a gene that codes for a polypeptide
• what is a chromosome

  the coiled section of DNA and histones
• what does homologous mean

  similar or the same
• what is a homologous chromosome

  a chromosome that has paired up with another that is the same size and has the same genes
• what is an allele

  an alternate form of a gene
• what is a histone

  circular proteins that combine with DNA to make a chromosome
• what is a genome

  the complete set of genes in a cell
• what is a proteome

  the full range of proteins produced by the genome
• describe prokaryotic DNA

  -short

  -circular

  -not associated with histones
• describe eukaryotic DNA

  -long

  -linear

  -associated with histones
• what is a degenerate code

  when amino acids are coded for by more than one triplet code
• why is the DNA code described as universal

  the triplets code codes for the same amino acid in all organisms
• what is splicing

  the removal of introns from pre-mRNA
• what is the function of mRNA

  it moves the genetic information out of the nucleus for translation to happen
• what is the structure of mRNA

  -single stranded molecule made of RNA nucleotides

  -no hydrogen bonds
• what is the function of rRNA

  site of protein synthesis
• what is the structure of rRNA

  forms the structure of ribosomes along with proteins
• what is the function of tRNA

  it transfers amino acids
• what is the structure of tRNA


  -single strand of RNA folded

  -contains hydrogen bonds between RNA nucleotides
• how many combinations of triplet codes are there

  -64

  -means that a number of different triplet codes can code for the same amino acid
• what type of replication does DNA undergo

  semi-conservative
• what does DNA helicase do

  hydrolyses hydrogen bonds
• what does DNA polymerase do


  forms phosphodiester bonds to make the polymer of DNA
• what is the process of DNA replication

  1) 2 strands of the DNA separate and DNA helicase hydrolyses hydrogen bonds

  2) Free nucleotides are attracted to their complimentary base

  3) Once the new nucleotides have lined up they are joined by DNA polymerase

  4) All the nucleotides joins to form a complete polynucleotide chain, two identical strands of DNA are formed
• what is conservative replication

  an original and a brand new strand
• what is dispersive replication

  new DNA on both sides
• what is the method for meselsohns and stahls experiment

  1) grow bacteria in a medium containing heavy nitrogen-15

  2) observed where the DNA settled after ultracentrifugation

  3) moved bacteria to a medium containing light nitrogen-14

  4) after one division they observed where the DNA settled

  5) repeated with the second division
• what is interphase

  period of the cell cycle between cell divisions
• what happens during growth phase 1

  -protein synthesis and the formation of mRNA

  -organelles replicate
• what happens during the synthesis phase

  DNA replication
• what happens during growth phase 2

  cell growth
• what are the four stages of mitosis

  prophase, metaphase, anaphase, telophase
• what is apoptosis

  if a problem can't be fixed the cell will kill itself for the good of the body
• what happens in prophase

  -chromosomes condense and become visible

  -nuclear membrane breaks down

  -spindle fibres appear and attach to the centromeres
• what happens during metaphase

  -spindle fibres attach to chromosome

  -chromosomes align on the equator
• what happens during anaphase

  -centromeres divide

  -spindle fibres shorten
• what happens during telophase

  -nuclear membrane reforms

  -chromosomes decondense

  -spindle fibres disappear