Genetics Flashcards
Describe double helix
A spiral molecule made of 2 strands of DNA joined by bases. Contains the genetic information in a linear sequence of chemical subunits called nucleotides
What are 4 bases in DNA?
Adenine
Thymine
Guanine
Cytosine
What is DNA?
Deoxyribonucleic acid. 2 strands of nucleic acids on sugar phosphate backbone formed in double helix.
What is a chromosome?
Strand of DNA and protein. The DNA and histones make up nucleosomes. The nucleic acid and histones are known and chromatin. The chromosome is almost 5cm long so it twists and twists and twist to form recognisable X shape.
What is a gene?
Section of DNA containing particular set of instructions related to bodily function
How do bases join together?
A-T for example join together by hydrogen/polar bonding (a weak bond)
How do bases join to the deoxyribose strands?
covalent bonds
What are 4 bases in RNA?
Adenine
Cytosine
Guanine
Uracil (instead of thymine)
Describe how DNA becomes protein
DNA - transcription - mRNA - travels out of nucleus and attaches to ribosome - translation in groups of 3. t RNA bring along the amino acid which forms string to make protein.
What are codon and anti-codon?
codon = mRNA anti-codon = tRNA
How many chromosomes in each cell?
23 pairs = 46 in total
What are stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
Describe mitosis cycle
Prophase - DNA organises and condenses into chromosome shape. Nucleolus disappears. Centrosomes start to form microtubules
Pro Metaphase - nuclear membrane breaks down. Microtubules attach to kinetocre
Metaphase - chromatids align along the middle
Anaphase - Microtubules shorten, pulling chromatids apart
Telophase - Now have 46 chromatids at each pole. Microtubules break down. Nuclear membrane forms at each end. Chromosomes uncoil into uncondensed state
Cytokinesis - division of cell
Describe interphase
G1 - growth phase
Cell performs functions and duplicates organelles
S - synthesis - duplicates DNA
G2 - grow to final size
What does meiosis produce?
Gametes - haploid cells. (23 single chromosomes)
What is process where genetic information is changed?
Crossing over during prophase I or called recombination