b) Inheritance

What is a genome?

All of an organisms DNA.

What is a gene?

A section of a molecule of DNA that codes for a specific protein.

Where are genes located?

They’re in chromosomes that’s re found in the nucleus.

What are alleles?

They’re different versions of the same gene giving different version of a characteristic.

Meaning of dominant allele?

The version of the characteristic that appears.

Meaning of recessive allele?

The version of the characteristic that doesn’t show.

Meaning of homozygous?

When you have two alleles the same for a particular gene.

Meaning of heterozygous?

When you have two different alleles for a particular gene.

Meaning of phenotype?

The characteristics the alleles produce.

Meaning of genotype?

The alleles you have.

How are phenotypic features formed?

From polygenic features instead on one single gene.

What is a monohybrid inheritance?

The inheritance of a single characteristic.

You can use a monohybrid cross to show how recessive and dominant traits for a single characteristic are inherited.

How to interpret family degrees?

Square = male

Circle = female

Shaded square and circle = has genetic disorder

Half shaded square and circle = genetic disorder carriers

Square and circle = unaffected and not carriers

How can you predict probabilities of outcomes from monohybrid crosses?

Use a punnet square

How does lettered chromosomes determine you gender?

XY = male

XX = female

How does mitosis of a diploid cell produce two cells?

DNA spreads out in long strings

Cell gets signal to divide so it needs to duplicate and DNA forms x-shaped chromosomes

Chromosomes line up at centre of cell and cell fibres pull them apart

Membranes form around each set of chromosomes

These become nuclei of two new cells

Cytoplasm divides

When does mitosis occur?

Growth, repairing, cloning and asexual reproduction of plants and animals.

Function of meiosis?

Produces four haploid cells whose chromosomes are not identical.

What happens at the 1st division of meiosis?

Duplicates its DNA

Chromosomes line up in pairs one from mother and one from father

Pairs are pulled apart

Each new cell now has mixture of mother and father’s chromosomes.

Mixing genes creates genetic variation in offspring

What happens in the seconds division of meiosis?

Chromosomes line up again

Arms of chromosomes are pulled apart

You get four haploid gametes

Each gamete only has a single set of chromosomes and are all genetically different

How does random fertilisation produce genetic variation of an offspring?

Since fertilisation of gametes is random and it inherits feature from both parents.

In human cells what is the diploid and haploid number?

Diploid = 46

Haploids = 23

Different types of variation within a specie?

Genetic

Environmental

Combination of both

What is mutation?

A rare, random change in an organisms DNA that can be inherited.

What is Darwin’s theory of evolution?

Life began as simple organisms from which more complex organisms evolved.

How does resistance to antibiotics increase bacterial populations?

Bacterium that can resist antibiotics can live longer and reproduce more. Leading to the allele for resistance being passed on and more common in a population of bacteria over time.