Topic 6 - Inheritance Flashcards
Where is genetic material stored?
The nucleus
What is the structure of DNA?
Double helix structure
What is a chromosome?
A 3D structure containing DNA
What is a gene?
A small section of DNA that codes for a sequence of amino acids to make a specific protein
What is a genome?
The entire genetic material for an organism
Why is it important to understand the genome?
To find genes which are linked to diseases , to treat inherited disorders and to understanding human migration patterns
What type of molecule is DNA
A polymer made from 4 types of nucleotide
What is a nucleotide made up of?
A sugar, phosphate and base
What provides the code for an amino acid
Three nucleotides code for one amino acid
Explain why most mutations do not result in non-functioning enzymes
Some DNA is non-coding therefore some genetic mutations will not result in changes to the phenotype
Which bases pair together?
A + T
C + G
Define sexual reproduction
Reproduction using gametes
Define asexual reproduction
Reproduction without using the gametes and creating a clone
What is a gamete?
A sex cell
What are the gametes in plants?
Male - pollen
Female - egg
What are the gametes in animals?
Male - sperm
Female - egg
Which type of reproduction leads to variation within offspring?
Sexual reproduction
How do you describe the offspring of asexual reproduction?
Clones
What is meiosis?
Cell division producing genetically different gametes
Why is meiosis important?
It will produce 4 gametes which are unique
Outline the process of meiosis
- Genetic information of cell in reproductive organ is copied.
- Cell divides twice.
- 4 genetically different gametes produced with single set of chromosomes
Name some organisms which can reproduce both sexually and asexually
Malarial parasites reproduce asexually in humans, but sexually in the mosquito.
Fungi reproduce asexually by spores, but also sexually to give variation. Many plants produce seeds sexually, but also reproduce asexually by runner or bulb division.
What is the difference between mitosis and meiosis ?
Mitosis produces 2 identical daughter cells but meiosis creates 4 gametes
Name some advantages of sexual reproduction
- produces variation in offspring, meaning a survival advantage if there is an environmental change, also can be used to human advantage in selective breeding.
Name some advantages of asexual reproduction
- Only one parent is needed, more time and energy efficient as organisms, faster the sexual reproduction, many identical offspring can be produced
How many chromosomes are there in a human body cell?
23 pairs, 46 individual
What does the 23 pair of chromosomes determine ?
Sex
What are the sex chromosomes for a female ?
XX
What are the sex chromosomes for a male ?
XY
List two things controlled by a single gene
-Eye colour
-Fur colour in mice
What is an allele?
Different forms of the same gene
What is a dominant allele?
An allele that will always be expressed in the phenotype
What is a recessive allele?
An allele that will only be expressed in the phenotype if two copies are present
What is a genotype?
Genotype is the combination of alleles in an organism.
What is a phenotype?
Phenotype is the observable features of an organism.
What is homozygous ?
Homozygous is two copies of the same allele.