A base (A) that is found in DNA, only bonds with Thymine (T) and this pairing forms part of the rungs of DNA
Reproduction of identical offspring from a single parent. No gametes are involved (e.g fission in bacteria, spores)
Thread-like structures bearing genes that are found in the nucleus of a cell. Visible during the prophase of cell division
Deoxyribonucleic acid. A molecule found in the nucleus of cells which codes for an individuals genetic makeup.
Are proteins that act as biological catalyst in living organisms. They control the rate of reactions
A sex cell: Ovum and sperm in animals or ovule and pollen grain in plants. A cell that has to join with another gamete to form a zygote before further development can occur
A base that is found in DNA. Guanine (G) will only bond with Cytosine (C) and this pairing forms part of the 'rungs' of DNA.
Having two identical alleles for a particular gene; breeds true when crossed with genetically identical organisms
Photograph of individual chromosomes of a cell arranged in pairs and showing their number, size and shape
The type of cell division which produces sex cells/gametes. In animals occurs in ovaries/testes. Process where diploid nucleus divides TWICE to produce four haploid, genetically different nuclei
A molecule containing a sugar-phosphate-base, found in DNA. Nuceotide bases pair to form DNA
The female organ that produces female gametes - eggs. Eggs are used in sexual reproduction in both plants and animals
Molecules that contain amino acids. They are found in all living organisms. There are many different types and all have important roles in living systems.
A diagram used to predict the phenotype and genotype ratios of offspring by showing how alleles combine together during fertilisation
DNA replication by 'unzipping' a DNA molecule followed by pairing up of nucleotides to produce two new DNA molecules each with one origional and one newly synthesised strand of DNA
Form of reproduction involving the fusion of two gametes from two parents. Produces a variation in the offspring
The male organ that produces male gametes - sperm. Sperm are used in sexual reproduction in animals
A fertilised egg. A single cell containing chromosomes from male and female gametes at the time/point of fertilisation
Used to find out the genotype of an individual. We cross the 'unknown' with a homozygous recessive and observe phenotypes of offspring.
Genotype and Phenotype ratio
Using the punnet square we write down the number/4 and % of individuals showing particular genotypes and phenotypes. i.e Genotype 2 BB: 2 Bb. Phenotype (100%) All Brown Eyed.
How is variation introduced in Meiosis?
Introduced through 1) independant assortment (each chromosome is organised into gametes independantly of each other chromosome), 2) Crossing over (homologous chromosomes - one from mum, one from dad - can switch genetic information creating chromsomes with new arrangment of genes) 3) Mutations - DNA can replicate with some errors 4) Fertilision - gametes produced in Meiosis come together to produce new/novel combinations.
Pair of chromosomes (same length, gene positions), i.e Chromosome #3, one comes from Mum, one from Dad.
Each chromosome is organised into gametes independantly of each other chromosome
This is when homologous chromosomes (one from mum, one from dad)can switch genetic information when they line up during cell division, this creates chromosomes with different arrangment of genes to parent chromosomes.
Can be either somatic (in body cells) or gametic (in gametes). Only Gametic mutations are passed on. This creates variation in a population. Natural selection acts on these new traits.
Explain what Natural Selection is and how it leads to evolution
More individuals are born than can survive. There is natural VARIATION in populations (not all the same). Some are BETTER SUITED to environment than others. Individuals COMPETE for resources. Those that are better suited produce MORE OFFSPRING. There genes are represented in greater proportion. Environment can change. This leads to gradual CHANGES (evolution) sometimes new species are formed.