Science genetics 2015
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what is MITOSIS?
Cell division for growth, repair and replacement of body cells. It results in two identical cells being produced which are also identical to the original or 'parent' cell.
What is MEIOSIS?
Cell division process to produce gametes (sex cells) for sexual reproduction. Results in four cells being produced which are all unique and contain the haploid number of chromosomes
During MEIOSIS homologous pairs of chromosomes line up in a random order and therefore when they separate into different gametes, it is by chance which one of the homologues goes into which cell.
a description of how the genotype is expressed. eg. tounge roller or non tounge roller
the alleles that represent a particular characteristic that an individual carries. e.g.
tt (homozygous recessive) Tt (hetrozygous), TT (homozygous dominant)
A length of DNA coding for a protein/feature/characteristic or trait.
A version of a gene. Eg. T - tongue roller; t - non tounge roller
Double stranded long molecule made up of nucleotides;found in the nucleus of cells;codes for an individual's make up
what is the base pairing rule?
DNA is made up of nucleotides. the babses always pair in the same combination.
- Adenine - Thymine (A-T)
- Guanine - Cytosine (G-C
A change to the DNA; can be caused by mutagens; is only passed on if it occurs in the gametes;a mutation is the 'ultimate' source of variation as it is the only source of new alleles
What is DNA replication?
A process which occurs prior to cell division to ensure that the full amount of DNA is present to produce new cells. After DNA replication, a single chromosome consists of two identical chromatids
what is a gamete?
A sex cell e.g Egg or sperm in animals. Needed for sexual reproduction; contains the haploid number of chromosomes so that when it fuses with another gamete, the diploid number is restored.
What is pure breeding?
Homozygous dominant or homozygous recessive - both alleles are the same for the gene. If two pure breeding organisms mate, they will only produce offspring of the same phenotype as the parents.
A characteristic or feature determined by an organisms genotype
Nucleotides are the building blocks of DNA. Each nucleotide is made up of a sugar, a phosphate, and a base. There are four bases; A-T and G-C
What is test cross used for?
used to determine whether an individual who shows the dominant phenotype is homozygous or heterozygous by crossing the individual with a homozygous recessive individual and then looking at the offspring.
differences between organisms within a population or species due to differences in the genetic code (order of the bases on DNA)
Define sexual Reproduction
reproductions requiring two parents - resulting offspring will carry a combination of the parents genes. Sexual reproduction will produce variety in a population or species
reproduction requiring just one parent. Offspring will be genetically identical to the parent and to each other - clones.
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