DNA and Gene Flashcards
(32 cards)
Human genome is made up of
Tow sets of 23 chromosomes
Genes are made up of
DNA
DNA is composed of
Phosphate (nucleotide)
Ribose sugar (nucleotide)
Base
Name the four bases
(A) Adenine (T) Thymine
(C) Cytosine (G) Guanine
Mutation
A sudden change in a chromosome or gene
heterozygous
Describes an organism with a pair of genes, where each is a different allele (i.e one dominant, one recessive)
phenotype
The visible, as opposed to the genetic, characteristics of an organism
Gene
A length of DNA coding for one protein
Replication
Process in which a DNA molecule ‘unzips’, then new bases are added to each side, and two identical molecules are formed
Allele
A ‘version’ of a gene. Each version codes for a different phenotype (e.g blue eyes, or brown)
Fertilisation
It happens when sperm and ovum come together, restoring the diploid number of chromosomes
Chromatids
Two identical copies of a chromosome, held together by the ‘centromere’, just before division
homozygous
An organism whose alleles for a particular gene are both the same
Mitosis
When a cell divides and produces two cells with identical chromosomes
Recessive
An allele whose feature, e.g. blue eyes, is only seen when there are two copies, (i.e. when homozygous)
Diploid
Describes a cell with two sets of chromosomes (a set from each parent)
Nucleus
The part of a cell which contains chromosomes
Gene(s)
They determine our inherited characteristics
Gametes
Sperms and ova (eggs)
Chromosome
Long strand of DNA, made up of many different genes. ONly visible when tightly coiled.
Genome
A name for the full set of genes possessed by an organism
Zygote
A fertilised egg cell
Meiosis
When a cell divides twice to produce four cells with only one set (u.e. half the normal number) of chromosomes.
What is the name of the basic unit of DNA?
nucleotide
