Inheritance Keywords

Allele

alternative form of a gene e.g. eye colour

Anticodon

part of tRNA that’s complementary to codon on mRNA

Chromosome

long coiled molecule of DNA that carries genetic information through genes

Chromatid

1 out of 2 strands of a replicated chromosome, become visible at the start of mitosis and meiosis

Codominance

When 2 different alleles are both expressed e.g. people with AB blood type, both the A allele and the B allele are equally expressed

Codon

3 base sequence to code for an amino acid

Diploid

A cell containing 2 sets of chromosomes e.g. a diploid human cell has 46 chromosomes

DNA (deoxyribonucleic acid)

double stranded polymer in a double helix that carries genetic code. Has bases A,T,C,G

Dominant

Allele that is always expressed

Evolution

Gradual change in inherited traits over time due to natural selection

Gene

Section of DNA that codes for a specific sequence of amino acids

Genome

Complete genetic material of an organism

Genotype

Organism’s genetic composition

Haploid

Cell containing 1 set of chromosomes e.g. human gametes have 23 chromosomes

Heterozygous

Having 2 different alleles of a gene e.g. Ff

Histone

Protein associated with DNA in a chromosome

Homozygous

Having 2 identical alleles of a gene e.g. ff

Meiosis

Form of cell division that produces gametes with half the usual number of chromosomes

Mitosis

Form of cell division that produces 2 genetically identical daughter cells. Involved in growth, repair, cloning and asexual reproduction

Monohybrid cross

Cross between 2 organisms that’s used to investigate inheritance of a gene

mRNA (messenger RNA)

molecule of RNA that has a complementary sequence to a specific DNA molecule. Formed in the nucleus, moves to the ribosome

Mutation

Random change in the structure of DNA which may result in genetic variant

Mutagens

Chemicals that increase frequency of mutations in DNA e.g. tobacco smoke

Natural selection

Process where certain traits from genes gradually increase in a population over time

Nucleus

Organelle that contains genetic material, controls cell activity

Nucleotide

Organic molecule made of sugar, base, and phosphate group

Phenotype

Organism’s observable characteristics, due to environment and genotype

Protein Synthesis

Formation of a protein from a gene

Recessive

Allele that’s expressed only in the absence of a dominant allele

Ribosome

Organelle which is the site of protein synthesis (transcription)

RNA

single stranded polymer with bases A,U,C,G

Selection Pressure

Organisms that have adapted to survive in their environments despite selective agents

Sex Chromosomes

23rd pair of chromosomes that determine sex of an individual, XX female, XY male

Sexual Reproduction

Type of reproduction that involves the fusion of gametes, creates genetic variation

Template Strand (DNA)

Strand of DNA that codes for proteins

Transcription

1st phase of protein synthesis, mRNA is made

Translation

2nd phase of protein synthesis, takes place in ribosomes

tRNA (transfer RNA)

Type of RNA that carries specific amino acids to ribosomes for translation

Test Cross

Cross between a dominant phenotype and a recessive homozygous to determine whether the the parent in homozygous or heterozygous

Variation

Difference between things due to either genes or environment