SB3 Flashcards
What is an allele
Different forms of the same gene
What is homozygous
2 same alleles
Eg ff
What is heterozygous
2 different alleles
Eg Ff
What is a dominant allele
Only 1 allele needed to be visible
What is recessive
2 alleles needed to be visible
What is a phenotype
Physical characteristics
What is a genotype
Allele combination
What did Mendel discover
Why didn’t people believe him
He discovered the foundations of genes
No evidence
No microscopes
Against church
What is it called when someone has a disease but it isn’t visible
A carrier
What is a more dominant blood type:
Ia or Io
Ib or Io
Ia or Ib
Ia
Ib
Neither they come together to make
Iab
What is the difference between haploid and diploid
Haploid is 23 chromosomes
Diploid is 46 chromosomes
What is meiosis a type of
Cell division
Where does meiosis happen
Reproductive organs
What happens in meiosis
- before the cell divides it duplicates its DNA
- the chromosomes line up in pairs in the centre of the cell
- the pairs are pulled apart so each new cell only has one copy of each chromosome
- the new cell will have a mixture of mother and father chromosomes
- then the chromosomes line up again in the centre of the cell
- the cells divide and 4 haploid dahughter cells are created
- these cells are haploid
What are the advantages and disadvantages of asexual reproduction
ADVANTAGES
produce a lot very quickly
only one parent is needed
DISADVANTAGES
No genetic variation
What are the advantages and disadvantages of sexual reproduction
ADVANTAGES
Genetic variation
DISADVANTAGES
Takes longer
Uses more energy
Fewer offspring
What is DNA made up of
What are nucleotide made of
Polymers made up of lots of nucleotides
Each nucleotide consists of one sugar molecule, one phosphate molecule and one base
The sugar and phosphate form a backbone to DNA strands
What are the 4 bases of DNA
Adenine
Thymine
Cytosine
Guanine
Describe the structure of DNA
Double helix
4 bases (AT and GC)
Hydrogen bonds
What is the size chart of
DNA
Gene
Chromosome
Nucleus
Nucleus
Chromosome
DNA
Gene
What are the two stages of protein synthesis
Transcription
Translation
Explain what happens during transcription
- A DNA polymerase binds to a region of non-coding DNA, unzips all the DNA
- It uses the template to make a mRNA
- The bases U (uracil) is used instead of T
The mRNA then leaves the nucleus through its pores and joins to a ribosome
Explain what happens during translation
- Amino acids are brought to the ribosome by tRNA
- the order in which the amino acids are brought to the ribosomes Mathew the order of the codons
- the anticodon is complementary to the codons
- the pairing of the codons and anticodon ensure the amino acids are brought to the ribosome in the correct order
- the amino acids join up creating a polypeptide
What is a mutation
A change in DNA and can be inherited
