Biology Level 1 Flashcards

Genotype

The allele combination (for a specific trait) at a particular locus on a chromosome.

Genetic Variation

The difference between the genes and alleles in a population

Meiosis

Cell division producing 4 genetically non-identical daughter cels, with a unique combination of alleles in the gametes.

Chromosomes

Long strands of DNA tightly wound together that carry genetic information in the form of genes. Each species has a characteristic number of chromosomes.

Allele

A specific version of the same gene.

Phenotype

The physical expression of a genotype.

DNA

A large molecule coiled into a double-helix structure made of ribose/sugar, phosphate and a base (A pairs with T and G pairs with C).

Mutation

A permanent base change in the sequence of a DNA strand.

Gene

A specific section of the DNA sequence. It codes for a specific trait.

Natural selection

The process where organisms with advantageous genes/alleles are more likely to survive and reproduce, passing on those traits.

Phylogenetic Tree

A diagram that shows the relatedness of organisms.

DNA sequencing

The process of finding out the order of bases in a strand of DNA.

Non-inheritable Variation

Variation that cannot be passed on; a mutation due to enviromental effect on somatic cells.

Genetic testing/screening

Using DNA sequencing to identify mutations in genes that could cause or increase risk of disease

Sexual reproduction

A biological process where offspring are produced through the combination of genetic material from 2 parents.

Carriers

Heterozygous individuals who ‘mask’ a recessive allele, meaning this could increase in frequency.

Population bottleneck

When a population undergoes a significant reduction in numbers due to a catastrophic event, resulting in less genetic variation.

Non-random (selective) Mating

Mating not due to chance; each mate has ‘chosen’ the other for a particular reason (eg. physical or genetic traits).

Independent assortment

When homologous chromosomes line up in the middle of a cell in a random order before separating into gametes.

Fertilisation

The fusion of 2 gametes (sperm & egg)

Inheritable variation

Variation in traits/ alleles / genes that can be passed on to offspring; variation that has occured in the gametes.

Founder effect

When a small number of individuals from a larger population establish a new, isolated population that is less genetically diverse.

Gene tracking methodology

Identifies the presence or absence of one or more genes, genetic markers or a DNA sequence. Used to monitor genetic variation to protect and increase a population.

Genetic marker

A specific DNA sequence with a known location on a chromosome. Can identify a mutation or be used in DNA fingerprinting / profilling to compare individuals.

Fitness

The ability of an individual to survive and reproduce, according to its enviroment.

Pure breeding

The organism is homozygous for the allele being studied

Asexual reproduction

Needs only 1 parent. Offspring are identical to the parent and each other (clones).

Crossing over

When homologous chromosomes exchange genetic material, producing new unique combinations of alleles