DNA
What does DNA stand for?
Deoxyribonucleic acid
How many daughter cells are produced in mitosis and meiosis
2, 4
What is an allele
A version of a gene
In a pedigree chart, what does a filled in circle mean?
An affected female.
Who suggested the theory of Evolution by natural selection?
Charles Darwin
Which bases pair with each other?
Adenine - Thymine
Guanine - Cytosine
Outline the purposes of mitosis and meiosis.
Mitosis - growth and repair
Meiosis - reproduction
How do you represent a dominant trait and a recessive trait in a genotype?
Dominant, capital letter
Recessive, lowercase letter
Why are males more likely to show X-linked disorders?
Only inherit 1 'X' chromosome. No opportunity to mask a trait.
Compare selection agent and selection pressure
Selection agent is an environmental factor acting on a population, whereas selection pressure is the effect the selection agent has on the population
What are the components of a nucleotide
Base pair, phosphate, sugar
List the stages of mitosis.
Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis
What is the difference between heterozygous and homozygous.
Heterozygous, genotype where the 2 alleles are different. Homozygous, genotype where the 2 allele combinations are the same.
Vitamin D resistance is an X-linked dominant trait.
Write the genotypes of a female with Vitamin D resistance, whose father was not affected, and a male without Vitamin D resistance.
Use the letter D
XDXd
XdY
Outline the 5 stages of natural selection
Variation - mutations in genes produce different traits
Adaptation - specific traits are better suited to certain environments
Competition - some traits give an organism an advantage
Survival - advantages increase likelihood of survival
Reproduction - More likely to survive = more likely to breed and pass on favourable traits to offspring
Describe the relationship between gene, DNA and a chromosome
Gene is a section of DNA, DNA is wound around protein to form chromosomes.
Explain how meiosis increases genetic variation.
Produces gametes that are genetically diverse via the process of crossing over and independent assortment.
Compare genotype and phenotype
Genotype - genes that code for a trait (the letters)
Phenotype - expression of a trait
A pedigree chart shows two unaffected parents with an affected offspring.
Explain whether the inheritance pattern is dominant or recessive.
(teachers to draw on the board)
Recessive (autosomal).
The parents must be carriers (heterozygous)
Identify and explain how the 4 pieces of evidence support the theory of evolution.
The fossil record, shows missing links between ancestral organisms and more recent organisms
Anatomical similarities, homologous structures are formed in similar ways and share similarities, but have different forms and functions- indicating common ancestor
Geo distribution, shows patterns of common ancestry & gradual change based on environment
Chemical similarities, more differences in DNA sequence indicate greater time since organisms shared common ancestor
Identify and describe three types of mutations. What type is likely to have the biggest impact
Point: Substitution - one base is replaced with another
Frameshift: Insertion/Deletion - a base is added/deleted
Explain how non-disjunction during meiosis can lead to a genetic disorder
In meiosis, chromosomes do not divide correctly which leads to having either an extra or less chromosome. The genetic disorder type depends on which chromosome is affected.
Two heterozygous parents have offspring. What are the possible offspring genotypes? Use the letter T.
Tt x Tt
25% Tt, 50% Tt, 25% tt
Construct a pedigree chart for the below scenario:
A normal man (Joseph) marries a woman (Rebecca) who is heterozygous for HD and they have four children. Two of their sons (Adam and Charles) are born healthy without HD. Charles marries a woman without HD, and they have a normal daughter. Joseph and Rebecca's daughter Tasha and their last son (James) both have HD. James marries a non-HD woman whose parents also do not suffer from HD. James and his wife have three children - a normal boy, a normal girl, and a son with HD.
Teacher to check.
- Affected: Rebecca, Tasha, James, James' son 3
A population of Galapogos Tortoises shows variation in neck length. Some tortoises have long necks and some have short. Rainfall in the islands drops dramatically, meaning food can only be found in tall cactii.
Apply the theory of natural selection to predict what will happen to the finch population.
selective agent - less rainfall = change in availability of food.
V - Neck length
A - Longer necks are better suited to reaching tall cactii
C/S/R - Tortoises with longer necks have advantage, are more likely to find food and survive in the environment, and pass on their favourable traits to future generations.