What does meiosis produce?
4 genetically different haploid gametes
How many divisions are there in meiosis?
2
What are the stages of meiosis?
- Dna replicates
- Cell divides
- Chromosomes line up in pairs in centre
- Pairs then pulled apart
- Cell divides again
- 4 haploid daughter cells made
Where is genetic info found?
In the nucleus of every cell
What is DNA?
Very tightly wound up chemical
What is a gene?
A short section of a chromosome which codes for a specific protein
What are the complementary base pairs in a double helix?
Adenine Thymine
Guanine Cytosine
What are the complementary base pairs joined together by?
Weak hydrogen bonds
What are the 2 main strands of a double helix called?
Backbones
What are the advantages and disadvantages of sexual reproduction?
Adv:
- variation in the population
Disadv:
- need to find a mate
What are the advantages and disadvantages of asexual reproduction?
Advs:
- don’t need to find a mate
- rapid reproduction cycle
Disadv:
- no variation in the population
What is the experiment for dna extraction?
- Grind small piece of fruit opening cells, gently causing no damage to DNA
- 1/4 fill boiling tube with fruit paste
- Fill to 3/4 full with salt and detergent
- Put in hot water bath for 10 mins
- Pour off resulting solution into test tube
- Carefully run ice cold ethanol down side
What does the salt and detergent do to the fruit paste?
The salt makes the dna stick
The detergent breaks down the cell membrane
What does the ice cold ethanol do to the dna?
Separates dna
What is an allele?
Different versions of the same gene
What is a genotype?
The alleles that make up a given feature
Eg. (gg/GG/Gg)
What is a phenotype?
The characteristics we see
What does homozygous mean?
2 alleles that are the same for a given feature
What does heterozygous mean?
2 alleles that are different for a given feature
What does dominant mean?
The allele which will be shown in the organisms features (GG/Gg)
What does recessive mean?
Two required for the characteristic to show (gg)
What is the genetic diagram called using alleles?
Punnet square
What pair of chromosomes determine someone’s gender?
The 23rd
What is the chromosome pair for females?
XX
