3 Genetics Flashcards
Allele
One of a number of alternative forms of a gene that can occupy a given gene locus on a chromosome. They differ from one another by one or only a few bases.
Chromosome
Single long molecule of DNA, associate with protein, that carries the genes in linear order.
Co-dominant
Pairs of alleles that both affect the phenotype when present in the heterozygous state.
Dominant
An allele that has the same effect on the phenotype when in either the homozygous or heterozygous state.
F1
first generation
F2
second generation
Gamete
General name for haploid sex cells, eggs, sperm cells and pollen grains.
Gene
The basic unit of inheritance by which hereditary characteristics are transmitted from parent to off-springs. Section of DNA which codes for a specific characteristic.
Genotype
The alleles possessed by an organism.
Heterogametic
The gender that has two different sex chromosomes in the pair, XY. This is the male.
Heterozygous
Having two different alleles at a gene locus.
Homogametic
The gender that has an identical pair of sex chromosomes, XX. This is the female.
Homologous
Chromosomes in a diploid cell which contain the same sequence of genes but are derived from different parents.
Homozygous
Having two identical alleles at a gene locus.
Locus
The specific position on a homologous chromosome of a gene.
Monohybrid Cross
A genetic cross involving only one characteristic.
Phenotype
The characteristics of an organism.
Pure breeding
Having a homozygous genotype. Usually used to describe a dominant phenotype.
Recessive
An allele that only has an effect on the phenotype when it is in the homozygous state.
Sex chromosomes
The pair of chromosomes that control the sex or gender of the individual. In mammals and some other organisms these are the X and Y chromosomes.
Sex linkage
The pattern of inheritance characteristic of genes located on the sex (X) chromosomes.
Test Cross
Using a homozygous recessive to test a phenotypically dominant phenotype to determine if it is heterozygous or homozygous.
Autosomes
The chromosomes other than sex chromosomes.
Diploid
pairs of chromosome called homologous pairs
Haploid
one chromosome from each homologous pair.
Mutations
random changes in base sequence of DNA which give rise to new alleles.
Genome
The whole of the genetic information of an organism
Genome Size
The total length of DNA in an organism.
The Human Genome Project
Determines the entire base sequence of all the human chromosomes
Sickle Cell Anemia
Caused by a mutation in on of the haemoglobin genes. An amino acid GLUTANIC has been substituted by VALINE.
Causes of mutations
Ionising radiation, X-rays, UV light and genic chemicals
PCR
Polymerase Chain Reaction copies and amplifies small samples of DNA. Only specific section is amplified through the use of a primer which binds to the complementary regions of DNA.
Restriction endonucleases
group of enzymes that recognise very specific sequences of DNA and cut both of the DNA stands at this point.
Requirements for gene transfer 4
1- the insulin gene
2- a plasmid
3- a host bacterium (E.coli)
4- 4 enzymes
Gene transfer (7)
1- plasmid cut with restriction enzymes to produce sticky ends
2- add insulin gene
3- join loose ends with ligase
4- recombinant plasmid- contains the plasmid genes plus the human insulin gene
5- insert into bacterium
6- bacterium cultured in large vat
7- filtered and purified: human insulin
GMOs
genetic code is (nearly) universal so it can be transferred between organisms
Benefits of GM
increase production- greater yield
resistant to a specific pest/ external element
Risks of GM
developing resistance
spread of antibiotic resistance
mutations
Risks of GM
developing resistance
spread of antibiotic resistance
mutations
Clone
a group of cells or organisms that are genetically identical because they have come from a single parent.
Cloning
naturally occurring- plants: cuttings/runners
animals- done after IVF: zygote divides and each will develop into an embryo
SCNT 3
Somatic Cell Nuclear Transfer used to clone adult animals.
1- removes nucleus from body cell
2- transplant nucleus into enucleated egg cell
3- egg cell behaves like zygotes and develop into mature frogs
Carrier
an individual that has a recessive allele of a gene.
Pure/ true breeding
a parent where the dominant phenotype is homozygous.
Pure/ true breeding
a parent where the dominant phenotype is homozygous.
Mendel
pea-plant
most gametes producing cells
are diploid
alleles are in pairs
in pairs
gametes are produced by
meiosis
gametes are
haploid and contain one allele from a pair
fusion of haploid gametes to form the zygote
restores the diploid number
random fertilisation
mixes alleles
Huntingdon’s
dominant
Haemophilia
chromosome X- recessive
Colour blindness
chromosome X- recessive
Cystic fibrosis
Recessive
Test Cross
to test whether a dominant phenotype is homozygous or heterozygous and ALWAYS crossed with the HOMOZYGOUS RECESSIVE
