Glossary Flashcards
(24 cards)
What is a gene?
A section of a chromosome that codes for a protein.
What is an allele?
The different versions of the same gene.
E.g. brown eyes, blue eyes, green eyes
Define chromosome
They are made of long lengths of DNA
Define DNA
Carries genetic instructions that are used to make structural or functional proteins. It is made of repeating nucleotides.
What are the three parts of a nucleotide?
Phosphate, 5C (Carbon) sugar, 1 of 4 bases (A - C - T - G)
What is a mutation?
A random, permanent change to the DNA base sequence.
Considered to be “the ultimate source of variation.”
Can be helpful, harmful or neutral
What is a genotype?
A set of genes in our DNA that is responsible for a particular trait/characteristic
What is a phenotype?
A physical/observable characteristics of an organism.
What is a gamete?
An organism’s reproductive cell.
Only carries one copy of each chromosomes.
Female gametes = ova/egg cell
Male gamete = sperm
What is a zygote?
Form through the fertilisation of ova by the sperm.
Contains genetic information necessary to form a new individual
Define dominant
A variant of a gene that masks or overrides the effect of a different variant of the same gene on the other copy of the chromosome
Define recessive
A variant of the gene that is masked or overridden by the dominant gene
Define homozygous
Two identical alleles
Define heterozygous
Having two different alleles
What is pure breeding?
When identical organisms that produce offspring of the same phenotype
What is meiosis?
The process where gamete cells are made that are used for sexual reproduction.
Type of cell division that results in genetic variation
How many daughter cells are produced in meiosis?
4 daughter cells from one parent cell.
Have half the number of chromosomes from the parent cell
What is mitosis?
Process of cell division for growth and repair.
How many daughter cells are produced in meiosis?
2 identical daughter cells from one parent cell
Define crossing over
The exchange of genes between homologous chromosomes.
The mixture of parental characteristics in offspring
Define independent assortment
The formation of random combinations of chromosomes.
The random order of homologous pairs line up on the spindle fibre
What is a punnet square?
A square diagram used to predict the genotype of organisms
What is test crossing?
Used by breeders to determine if the dominant phenotype has a genotype of homozygous dominant or heterozygous
e.g. Hh or HH
What is a pedigree chart?
Looks at the genotype of past generations.
Used to determine whether traits are dominant or recessive
