Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
17 Cards in this Set
- Front
- Back
|
Components of DNA |
Deoxyribose Phosphate group Organic base - Adenine, Guanine, Cytosine, Thymine
Joined by a condensation reaction |
|
|
Base Pairing |
All contain nitrogen
Adenine - Thymine 2 hydrogen bonds Guanine - Cytosine 3 hydrogen bonds |
|
|
Double Helix structure |
Structural backbone of phosphate and deoxyribose For each turn is 10 base pairs Protects the DNA from corruption Joined by hydrogen bonds that are easily broken |
|
|
Genes |
Section of DNA that codes for a polpeptide which in turn combine to make proteins |
|
|
Triplet Code |
Minimum 3 bases for each amino acid - 20 regular amino acids - each amino acid must have its own code - only 4 bases - only 4 amino acids would be coded for if each base was a single amino acid - 4^2 = 16 which is not enough - 4^3 = 64 which is enough
Therefore the bases are coded in terms of three |
|
|
Define degenerate code |
Amino acids have more then one triplet code/sequence of bases |
|
|
Chromosomes found in: |
Prokaryotic - DNA found as plasmids, and not associated with proteins molecules so do not have chromosomes Eukaryotic - DNA is larger and form a line not a circle, associated with proteins so form chromosomes |
|
|
Chromosome structure |
When visible it appears as two threads - chromatids
DNA - PROTEIN complex as DNA wraps around proteins which is then coiled and packaged into a chromosome |
|
|
Homologous chromosomes |
Pairs of chromosomes that code for genetic characteristics NOT necessarily identical |
|
|
Allele |
A different form of a gene |
|
|
Meiosis importance |
Needed to maintain the correct number of chromosomes in a single cell for each species |
|
|
Haploid vs Diploid |
Haploid - in meiosis it's half the number of chromosomes
Diploid - restored during fertilisation as 2 haploid cells come together, the original number of chromosomes |
|
|
Crossing over |
Metaphase 1 Tension built up as chromatids wrap around one another at the tips and break |
|
|
Random Segregation |
Metaphase 1 Chromosomes line up in homologous pairs but do so randomly |
|
|
Meiosis metaphase 1 |
Random Segregation Crossing Over |
|
|
Meiosis metaphase 2 |
Chromatids separate and form 2 new haploid cells |
|
|
Features of meiosis |
4 daughter cells Half the number of chromosomes 2 stages of division Homologous pairs |
