Heredity, DNA, Genetics, Evolution

unit 2

Species 

a group of similar organisms capable of inter-breeding and producing fertile offspring 

Variation 

Differences in the characteristics of the species 

Heredity

the passing on of features from parents to their offspring through the means of genetics 

Genes 

a section of DNA made up of a collection of codons that contains the genetic code to form a protein and so controls a particular characteristic

Gene expression 

The way in which the genetic information in a gene is decoded in the cell to make a protein

Non coding

DNA that does not cause the production of a protein

Coding DNA

The part of the chromosome which carries the information to make a protein

DNA profiling

A method of making a unwise pattern of bands from a person’s DNA which can be used to distinguish that DNA from other DNA 

Genetic screening

Test to establish the presence or absence of a gene or an altered gene

Transcription

The copying of a sequence of genetic bases from a single strand of DNA onto mRNA

Translation 

the conversion of of a sequence of genetic bases on mRNA into a sequence of amino acids 

Anticodon

Sequence of three bases on tRNA that are complementary to three bases on mRNA

Gametes

A haploid cell capable of fusing with another gamete to produce a zygote (2n)

Fertilisation

Fusing of two haploid gamete to form a single diploid cell called a zygote

Alleles

Alternative forms of the same gene

Locus

The position of a gene on a chromosome

Dominant 

Always expressed and masks a recessive partner

Recessive

When an alleles expression is masked by a dominant allele.

Genotype

the genetic makeup of an organism

Phenotype

The physical appearance of an organism

Progeny

Offspring produced

Homozygous

Alleles are the same 

Heterozygous

Alleles are different 

Incomplete dominance

The allele is neither dominant nor recessive. Produces an intermediate progeny

Mendel’s first law (segregation)

Inherited characteristics are controlled by pairs of factors/alleles which separate at gamete formation. Only one member of each pair is found in each gamete

Mendel’s second law (independent assortment)

Gamete formation: Either member from a pair of factors can combine with either member of another pair of factors and both factors then enter the same gamete

Linkage

Genes are located on the same chromosome

Sex linkage

That a characteristic is controlled by a gene on the X chromosome 

Mutation 

A change in the structure or amount of DNA

Mutagens 

Agents that cause mutations

gene/point mutations

Changes in a single gene

Chromosome mutations

Large changes in the structure or number of one or more chromosomes

Evolution

The way in which living things change genetically to produce new forms of life over long periods of time

Natural selection

Where organisms have genetically controlled characteristics that allow them to adapt to their environment so they will survive and pass on their genes to future generations.

Genetic engineering 

The artificial manipulation or alteration of genes