Biology: Variation, Genetics, Inheritance

Variation meaning

Differences between individuals or groups of the same species.

What are characteristics determined by?

The genes inherited from the organisms parents.

Genetic variation

The combining of two genes from two parents

Interspecific variation

Variation between different species

Intraspecific variation

Variation between same species

Genotype

Set of alleles an organism has for a particular gene, determining its genetic makeup

Phenotype

Outward expression of the genotype, physical

Alleles

Version of a gene that determines characteristics

Sources of Variation: Genetics

Inherited, determined by genes inherited, control the development of our characteristics, each characteristic is controlled by a single gene.

Sources of Variation: Environment

Characteristics can be altered and changed. (Tattoos, scars)

Sources of Variation: Genetic and Environment

Determined by the effect of our inherited genes and our lifestyles

Types of variation: Continuous

Range of many intermediates between two extremes, controlled by many genes interacting together, can also be affected by the environment. (Height, Weight, Skin Tone)

Types of Variation: Discontinuous

No intermediates between them, controlled by many genes, environment has little or no effect. (Blood group, eye colour)

DNA meaning

Genetic material in the nucleus of a cell.

What is the same of a DNA?

Polymer. Large molecule made up of repeating subunits in the case of DNA, these are nucleotides.

Shape of DNA

Double Helix, two strands which spiral round.

Chromosomes

Structure where DNA is contained in.

Gene meaning

Small section of DNA on a chromosome.

What do genes do?

Code for a particular sequence of amino acids, to make a specific protein.

Genome meaning

The entire genetic material of an organism.

What is the Human Genome Project?

International scientific research project with the goal of determining the sequence of chemical base pairs, which make up human DNA.

Importance of studying Human Genome

It allows scientists to search and identify genes that are linked to different types of disease.

Knowing what genes are linked to inherited diseases, how to develop treatment

Trace the migration of certain populations of people around the world

How does the human genome change?

As different populations of people migrate away from Africa.

What did the completion of the HGP lead to?

Mapping, screening, medicine, ancestry

One molecule of DNA is made from what?

Two polynucleotide strands, which are linked together and wound into a double helix.

4 different nucleotides

Adenine (A), Thymine (T), Guanine (G), Cytosine (C)

Nucleotides consist of

Common sugar, phosphate group, with one of 4 different bases.

Attached to each sugar in DNA is what

One of 4 bases

Long polynucleotide strands of DNA consist of

Sugar and Phosphate sections

What do 3 consecutive bases code for?

A specific amino acid

Order of the bases control the order in which…

Amino acids are assembled to produce a particular protein.

Gene

Sequence of DNA that codes for specific sequence of amino acids to make specific protein.

Locus

The position of a gene on a particular chromosome

Proteins are synthesised in the cell in the…

Ribsomes

Transfer RNA (tRNA) also known as carrier molecules do what?

Bring specific amino adds to add to the growing protein chain in the correct order as coded for.

When the protein chain is complete,….

It folds up to form a unique shape.

Triplet

DNA with ATCG bases

Codon

RNA with AUCG bases

mRNA make a copy of what?

DNA

Mutations are…

Alterations to the base sequence in the DNA

Gene mutation is…

A change in the nucleotide sequence of a section of DNA

Point mutations are…

Changes to one base in the DNA code

What may involve with point mutation?

Substitution, Insertion, Deletion, Inversion

Silent mutation

Occur when the DNA change does not alter the amino acid sequence of the polypeptide.

Why does silent mutation happen?

Genetic code is degenerate and certain codons may code for the same amino acid.

Missense mutation is…

DNA change alters a single amino acid in the polypeptide chain

An example of a disease caused by a single base substitution mutation

Sickle Cell Anaemia

Nonsense Mutations are…

DNA change creates a premature STOP codon which truncates the polypeptide.

An example of a disease which can result from a nonsense mutation

Cystic Fibrosis

Point mutation: Beneficial mutation

Change the gene sequence to create new variations of a trait.

Point mutation: Detrimental mutations

Stop the gene sequence and prevent the proteins from functioning normally

Point mutation: Neutral mutations

Have no effect on the functioning of the specific protein.