3b Flashcards
Genome
Entire DNA of an organism
Gene
Section of DNA molecule that codes for a specific protein
DNA molecule
- Two strands coiled to form a double helix
- Strands linked by:
- Adenine(A) & Thymine(T)
- Cytosine(C) & Guanine(G)
RNA molecule
- Single stranded
- Contains Uracil (U) instead of thymine (T)
Allele
Alternative form of a gene
Dominant
An allele that is always expressed
Recessive
An allele that needs 2 copies to be expressed
Homozygous
Two of the same allele
Heterozygous
Two different alleles
Phenotype
What an organisms looks like
Genotype
Which alleles an organism has
Codominance
Alleles that are both expressed in the same phenotype. E.g. blood groups
Polygenic inheritance
Features that are controlled by multiple genes with many alleles. E.g. eye colour, skin colour
Diploid number of chromosomes in human cell
46
Haploid number of chromosomes in human cell
23
Mutation
A rare, random change in genetic material that can be inherited
Mutation chance can be increased by:
- Exposure to ionising radiation
- Chemical mutagens
Chromosome
Carries genetic information in the form of DNA
Transcription
- A protein splits DNA into two strands.
- From one of the two strands, an mRNA strand is constructed (everything remains equal to the other half but it binds adenine with uracil instead of thymine).
- This creates a messenger RNA (mRNA) strand
Translation
- Ribosome binds to mRNA
- Transfer RNA(tRNA) reads the mRNA strip 3 bases at a time
- It attaches the corresponding amino acid of the 3-base pair to an amino acid chain
- A protein is synthesised from the amino acid chain
Natural Selection
The process in which a species becomes better adapted to its environment.
- Variation from mutations
- Adaptation for selection pressure (temperature, diseases, competition for food…)
- Best adapted survive
- Reproduce
- Pass on alleles
- Repeated over multiple generations
Codon
3 base pair that codes for an amino acid, found in mRNA.
Anticodon
Complimentary 3 base pair found in tRNA. Matches with codon during translation
