Genetics Review 12U Bio

Induced mutations

Result from the influence of an unrelated factor or agent, either natural or artificial

Spontaneous mutations

Happen naturally and randomly, arising from replication error and base modifications

Somatic mutations

occur in any cell except germ cells and are not heritable

Germ-like mutations

Occur in gametes and are inherited

Missense mutations

Change a codon resulting in altered amino acid

Nonsense mutation

changes a codon into a stop codon and results in premature termination of translation

Silent mutation

Alters a codon but does not result in a change in the amino acid at that position of the protein

Point mutations

Fibrodysplasia Ossificans Progressiva - point mutation in a bone morphogenetic protein type I receptor

Frame shift mutation

Result from insertions or deletions of a base pair. Eg.

DNA replication errors

DNA polymerase occasionally insets incorrect nucleotides, generally due to base mispairing
- Lead to point mutations

Slippage

During replication can lead to small insertions or deletions

Transposons

Genes that can "jump" within chromosomes and insert themselves into various positions, potentially causing mutations

Induced mutations

Arise from DNA damage caused by chemicals and radiation

Translation

Process by which mRNA is decoded and a protein is produced

Codon

A three base sequence on the mRNA use to code for one amino acid

Anticodon

A three base sequence on the tRNA used to recognise and bind to the codon as each amino acid is added

Polypeptide

A linked chain of amino acids created in the ribosome

Ribosome

The location where translation takes place

Start Codon

A first 3 base sequence that starts all genes; AUG

Stop Codon

A 3 bases sequence found at the end of each gene; UAA, UAG or UGA

Amino Acids

The units that make up a protein; each amino acid is coded for by one codon

Purine

has 2 rings (Adenine and Guanine)

Pyrimidine

has 1 ring (Thymine and Cytosine)

Difference between RNA and DNA

RNA us "U" instead of "T"

Transcription

The process by which the message from DNA is written down into RNA

mRNA (messenger RNA)

The form of RNA which is created as a blueprint from DNA; carries instructions for making a protein

Uracil (U)

The base found only in RNA (replaces thymine in DNA)

Nucleus

The location where transcription takes place

RNA editing

A process that takes place before the mRNA is sent to the ribosome; some RNA bases are removed in order to create a final draft of the mRNA

Introns

The sections of RNA removed from the final draft of mRNA that remain in the nucleus

Exons

The sections of RNA that make up the final draft of mRNA which is sent out of the nucleus to the ribosome

RNA polymerase

The main enzyme that transcribes DNA into mRNA

One

Number of strands RNA is made of

5' to 3'

The direction mRNA is synthesized

DNA 3' ATG CGT TAG 5' transcribes to

5' UAC GCA AUC 3'

rho protein

RNA binding protein responsible for terminating transcription

5' cap

a methylated guanine nucleotide added to the 5' end of eukaryotic mRNA

Poly-A tail

Prevents mRNA from being degraded in cytoplasm
100-250 A's at 3' end

spliceosome

complex of enzymes that serves to splice out the introns of a pre-mRNA transcript

SNRP

Small nuclear ribonuclear peptide

Shape of DNA

a double helix.

Nucleotide

sugar covalently bonded to a nitrogenous base and a phosphate group.

Nitrogenous base

A nitrogen containing molecule that is a part of nucleotides

Complementary Base to Adenine

Thymine

Complementary Base to Cytosine

Guanine

Backbone of DNA is made of

Deoxyribose sugar and phosphate

Rungs of ladder are made of

Nitrogen bases

Nucleotide

Diagram

The complimentary DNA strand of the following is:
ATT TAA ACC GAG

TAA ATT TGG CTC

The complimentary DNA strand of the following is:
GGG CCC AAA TTT

CCC GGG TTT AAA

Nucleotide

DNA

Contains ATCG, A Deoxiribose Sugar, and is double stranded

Gene

A section of DNA that codes for a trait

T

The Base Pair A matches with

C

The Base Pair G matches with

DNA Back Bone

Made from Phosphate and Deoxiribose

origin of replication

a particular sequence in a genome at which replication is initiated

replication fork

A Y-shaped region on a replicating DNA molecule where new strands are growing.

replication bubble

an unwound and open region of a DNA helix where DNA replication occurs

helicase

separate double-stranded DNA into single strands allowing each strand to be copied; unzips dna

gyrase (topoisomorase)

relieves strain while double-stranded DNA is being unwound by helicase. This causes negative supercoiling of the DNA

single-stranded binding protein

prevent ssDNA from re-forming a double helix; speeds up replication

primase

functions by synthesizing short RNA sequences that are complementary to a single-stranded piece of DNA; primer for dna polymerase

primer

a short strand of RNA that serves as a starting point for DNA synthesis

deoxynucleoside triphosphate

individual nucleotides with three phosphate groups

5 to 3 direction

direction new DNA is formed. The 5' carbon has a phosphate group attached to it and the 3' carbon a hydroxyl (-OH) group

dna polymerase III

enzyme that builds new DNA strand

dna polymerase I

removes the RNA primer and fills in the nucleotides which are necessary for the formation of the DNA in the direction- 5' to 3'. It also helps in proof reading to see if there is any mistake done while replication and while matching base pairs

okazaki fragments

short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication.

ligase

seals repairs in the DNA, it seals recombination fragments, and it connects Okazaki fragments

Helicase

unwinds DNA

Ligase

Joins Okasaki fragments

Primase

creates RNA primer

DNA Polymerase

creates new DNA strands

leading strand

DNA created towards the replication fork

Lagging strand

DNA created away from the replication fork

Okasaki fragment

Short segment of DNA on lagging strand

RNA primer

Binding site for DNA polymerase