Paper 1 - Inheritance Flashcards
What is the genome?
The entire DNA of an organism
What is a gene?
A section of a molecule of DNA that codes for a specific protein
What does the nucleus of a cell contain?
Chromosomes on which genes are
located
In what alternative form do genes exist?
- As alleles
- Which give rise to differences in inherited characteristics
What does dominant mean?
An allele that is always expressed even if there is only 1 of them (use a capital letter)
What does recessive mean?
An allele that is only expressed when there are 2 of them
What does homozygous mean?
Having either 2 dominant or 2 recessive alleles
What does heterozygous mean?
Having 1 dominant and 1 recessive allele
What does phenotype mean?
What you can visibly see expressed
What does genotype mean?
All the alleles that make up an organism
What are most phenotypic features a result of?
Polygenic inheritance rather than single genes
How is the sex of offspring controlled by one pair of chromosomes?
- XX for female
- XY for male
What does the division of a diploid cell by mitosis produce?
Two cells that contain identical sets of 46 chromosomes
When does mitosis occur?
During :
- Growth
- Repair
- Cloning
- Asexual reproduction
What does the division of a cell by meiosis produce?
4 daploid daughter cells, each with 23 chromosomes
What does the division of a cell by meiosis result in?
The formation of genetically different
haploid gametes
How does random fertilisation produce genetic variation in offspring?
- Random variation
- Different combinations of sperm and egg produce different zygotes
- Different zygotes create different phenotypes
How many chromosomes does a gamete have?
23
How many chromosomes does a haploid cell have?
23
How many chromosomes does a diploid cell have?
46
What causes variation within a species?
- Genetics
- Environment
- Or a combination of both
What is mutation?
Mutation is a rare, random change in genetic material that can be inherited
Explain Darwin’s theory of evolution by natural selection
- Variation in organisms is caused by mutation
- Selection pressure is put on organisms
- Food sources were different on each other Galapagos Island’s
- Depending on the food source type on the island, a certain characteristic would have been more advantageous because it gives the organism an advantage.
- These individuals are more likely to survive and reproduce
- Advantageous alleles are passed on to offspring
How can resistance to antibiotics cause an increase in bacterial populations?
- Random mutation gives a bacteria immunity to an antibiotic so that bacteria survives and reproduces
- Passes on advantageous alleles to offspring so offspring are immune as well
- Non-immune bacteria die and then all bacteria are immune to antibiotics so bacterial population increases
