DNA Flashcards
How many chromosomes do humans have?
23 pairs
46
Describe the structure of a DNA strand
-2 polymer strands
-joined together by bonds between the bases
-double helix
Describe the structure of a DNA monomer
A phosphate with a sugar attached to a base
What are the 4 bases called
Thymine + adenine, guanine + cytosine
How many bases create an amino acid?
3
Describe the copy and transfer of dna from the nucleus to the ribosomes (protein synthesis)
1- the dna strands separate
2- the free RNA line up opposite the complementary exposed bases
3- the RNA nucleotides are joined together to make a polynucleotide strand called mRNA (à copy)
4- the mRNA breaks away from the dna and the strands join together again.
Describe what happens to mRNA in the ribosomes.
1- the mRNA travels out of the nucleus into the ribosome.
2- tRNA picks up the amino acids and delivers them to the ribosomes in the order that the mRNA tells them to.
3- only then can they enter the ribosomes
Name some mutagens
UV radiation
X-rays
HPV
Benzoyl peroxide
Why is the specific shape of the dna important?
It dictates how the polypeptide chain will fold. If one is wrong it will fold incorrectly and not function properly.
Describe substitution
Swaps one base for another which means a different code and a different amino acid.
It depends where it is for the changes to impact
Describe insertion/deletion
1 or more nucleotides are lost or added to the sequence.
Due to the fact that DNA is read in 3s, it means it effects all subsequent codes. This means it’s read wrong.
What is a gamete?
A specialised cell with 1 set of thr parents chromosomes eg a sperm cell
What happens in MEOSIS?
They both start with the chromosomes replicating. The pairs of chromosomes are separated (like in mitosis).
During the second division, the sister chromatids (arms) get split up and swapped slightly. This creates 4 unique gametes.
What did Mendel discover?
He found out some characteristics were dominant due to his research with pea plants.
What is an allele?
Different forms of the same gene
What does homozygous mean?
An organism has two alleles for a particular gene that are the same.
What’s à genotype?
What alleles you have eg Tt
What’s à phenotype?
The characteristics you have eg blue eyes.
What is a treatment for cystic fibrosis?
Physiotherapy
Taking nutrient pills
Taking enzymes
Name a genetic condition caused by a dominant allele
Polydactyl
