Genetics Inheritence Flashcards
(32 cards)
What are chromosomes?
Structures within a cell nucleus that contain DNA (genetic information)
What is a gene?
A specific sequence of DNA. They code for a specific protein or RNA.
What are gene variants/alleles?
They have different DNA sequences than the ‘normal’ gene
What is genetics?
The study of genes, genetic variation, and heredity
What is heredity?
The transmission of traits from one generation to the next
Why is Gregor Mendel the father of genetics?
He was the first person to experimentally analyse patterns of inheritance using pea plants as his model system in 1866
What is a model system?
An organism that makes it easy for a researcher to investigate a particular scientific question
They then apply their findings to harder to study organisms
What is the blending model of inhertiance?
Inheritance involved the permanent blending of parents’ characteristics in their offspring
Why was the blending model full of holes?
Could not explain why when Mendel crossed a pure bred tall and short pea plant, he only got pea plants
Also could not explain why self fertilisation of the above tall plants would produce a 3;1 ratio of tall to short plants
What does true breeding mean in terms of mendelian genetics?
An organism must be homozygous for every trait for which it is considered true breeding
How are peas cross-pollinated and self pollinated?
Cross: Transfer pollen with brush then remove anthers
Self: Transfer own pollen to own stigma
Which traits of pea plants did mendel observe?
Format: Trait - Dom trait vs Rec trait Colour - Purple vs white Position - Axial vs terminal Seed Colour - Yellow vs Green Seed Shape - Round vs Wrinkled Pod Shape - Inflated vs Constricted Pod Colour - Green vs Yellow Stem Length - Tall vs Dwarf
What are hybrids?
The offspring of two different purebred varieties
How did Mendel determine the flower trait colour dominancy?
P Generation was with purebred white and purp
F1 generation was all power
F2 generation was 3:1 purple to white
What is the difference between phenotype and genotype?
Phenotype is what we see
Genotype is the actual allele distribution
What are Mendel’s 4 hypotheses?
- The alternative versions of genes are called alleles
- For each trait, an organism inherits two alleles, one from each parent. This organism is now diploid (remember gametes are haploid)
- If 2 alleles differ, only the dominant allele determines the phenotype
- 2 alleles in a diploid parent separate from each other so that their gametes only have one allele (haploid)
What is a Punnet Square?
A diagram used to predict outcomes of a cross breeding. It shows the combinations of gametes and the possible resulting offspring
What is complete dominance?
If this allele is present, it will display it’s phenotype over the recessive gene
How does genes relate to cystic fibrosis?
CF is a recessive genetic disorder. the C allele produces a normal function CFTR gene. A person with Cc is a carrier. A person with cc has CF, and both parents must have been carriers or have CF.
What is incomplete dominance?
Heterozygotes have an intermediate appearance between the two parents
An example would be snapdragon flower colour (RR = red, rr = white, Rr = pink)
What is co-dominance?
Both alleles are expressed in a heterozygous individual
An example would be blood cells (AA = A, BB = B, AB = AB)
If you receive incompatible blood, _____ occurs
clumping
For example, people of A has Anti B antibodies, meaning any B blood would clump (B/AB)
Describe the genetic makeup of bacteria vs eukaryotes
Bacteria: 1 circular chromosome, compact genome, no meiosis, exchange genetic material through conjugation, transformation, and transduction
eukaryotes: Often diploid, large genomes, meiosis, genes change though meiosis and fertilization
What are plasmids?
Small circular pieces of DNA
