Genetics Flashcards
(41 cards)
What is a nucleotide?
A monomer that joins together with other nucleotides to form DNA
What is a mutation?
A change in the order of bases on a strand of DNA which affect anything that the DNA section codes for
What is substitution?
When one base is changed for another
What is meiosis?
A type of cell division that results in four daughter cells each with half the number of chromosomes as the parent cell and is used to create gametes. For example, a sperm cell has half the number of chromosomes as a normal body cell. Meiosis produces haploid cells
What is the base pairing for DNA?
AT, CG
What is the base paring when producing a strand of mRNA?
AU, CG
What are the stages of meiosis?
- Each chromosome is copied
- The chromosomes move to the edges of the cell
- The pairs of chromosomes divide into two separate cells
- These cells divide again into two more cells with half the number of chromosomes, these cells or gametes only have one copy of each chromosome
What is an allele?
A variant of a gene from your parents
What does heterozygous mean?
When chromosomes of the same pair have different alleles of the same gene
What does homozygous mean?
When chromosomes of the same pair have the same alleles of the same gene
What is a genotype?
Shows the alleles in an individual. For example Bb or bb
What is a phenotype?
The characteristics that are produced as a result of the alleles that the individual has
What is a zygote?
A fertilised egg
What is a recessive allele?
An allele that doesn’t show any impact unless paired with another of the same recessive allele. For example you two alleles that give you blue eyes for you to have blue eyes.
What is a dominant allele?
An allele that takes control/the one that is seen when the genotype is anything apart from two recessive alleles. It takes dominance over the recessive alleles
How do you work out the probability of having a particular genotype?
Using a Punnett square
What is co-dominance?
This is when there are two different dominant alleles and they both take dominance, creating a new genotype. This is most common in blood groups
What is cystic fibrosis?
A genetic disease and mutation that cause a build up of mucus in many organs and other small passages
What causes cystic fibrosis?
When both copies of the CFTR gene are faulty. If only one is faulty then they don’t have the disease but are a carrier
What is genetic modification?
A process used to copy desired characteristics from one organism to another
How does genetic modification work?
Certain enzymes can cut pieces of DNA with a desired characteristic from one organism, and join them into a gap in the DNA of another organism. This means that the new organism with the inserted genes has the genetic information for one or more new characteristics. For example, the organism might produce a useful substance, or be able to carry out a new function.
What was Mendel’s experiment?
- He created pure-bred peas to use in his experiment
- He cross-bred pure-bred dwarf peas with pure-bred tall peas to make the first generation of peas in his experiment and discovered that all offspring were tall. The allele for tall peas was dominant and the allele for dwarf peas was recessive
- Mendel then removed all the pure-bred peas and cross-bred the offspring with other offspring to make the second generation. Around 25% of the second generation were dwarf peas. This was because the first generation were carriers of the allele that makes dwarf peas
What chromosomes does a male have?
X, Y
What chromosomes does a female have?
X, X
