6.2 - B - Patterns Of Inheritance Flashcards
What is a genotype?
What is a phenotype?
Genetic makeup of an organism
Visible characteristic of an organism
What are mutagens?
What do they do?
Certain physical and chemical agents.
Increase the rate of mutation.
Name 3 physical agents, chemical agents and biological agents
X rays, gamma rays, UV light.
Benzopyrene (tobacco smoke), mustard gas, nitrous acid.
Some viruses, transposons, food contaminants.
What are transponons
Jumping genes, remnants of viral nucleic acid that have become incorporated into our genomes
Mutations during gamete formation are:
Persistent - they can be transmitted through many generations without change.
Random - they are not directed by a need on the part of the organism in which they occur.
List and define the 7 types of chromosome mutations
Deletion - pieces of chromosomes are deleted.
Inversion - flipping 180°.
Translation - a piece of chromosome breaks off and then attaches to another chromosome.
Duplication - pieces of chromosomes are duplicates.
Non-disjunction - one pair of chromosomes/chromatids fails to separate, leaving one gamete with an extra chromosome. This causes Down syndrome.
Aneuploidy - chromosome number is not an exact multiple of the haploid number. Sometimes chromosomes/chromatids fail to separate during mitosis (eg. trisomy).
Polyploidy - if a diploid gamete is fertilised by a haploid gamete, the resulting zygote will be triploid. The fusion of 2 diploid gametes makes a tetraploid zygote.
What are the 3 points during meiosis where genetic variation may result from?
Allele shuffling (swapping of alleles between non-sister chromatids) during crossing over in prophase 1.
Independent assortment of chromosomes during metaphase/anaphase 1.
Independent assortment of chromatids during metaphase/anaphase 2.
What does random fusion of gametes create?
More genetic diversity
Define monogenic
Determined by a single gene
What is a gene locus
The position of a gene on a chromosome
Define heterozygous
Having different alleles at the same gene locus on a pair of homologous chromosomes
Define homozygous
Having identical alleles at the same gene locus on a pair of homologous chromosomes
Define true-bred
Homozygous
Define dominant
Masks the effects of recessive alleles (big letter)
Define recessive
Masked by dominant alleles (little letter)
Define F1
First generation of offspring (to original parents)
Define F2
Second generation (offspring of F1)
Which way round do the genders go on a Punnett square?
Females down side/males along top
Give 5 features of continuous data
No defined categories/distinct groups.
There is a range ‐ any value is possible.
Caused by more than one gene (polygenic)and often, the environment.
The greater the number of gene loci contributing to the characteristic, the greater the range in variation.
Quantitative.
Give 5 features of discontinuous data
Discrete categories with no intermediates.
Usually caused by one gene (mongenic).
Genes at different loci may interact to influence one characteristic and
cause discontinuous variation (epistasis).
No (very little) environmental effects cause it.
Qualitative.
What did Mendel base his study on?
Pea plants
Define dihybrid
Involving 2 gene loci
To use Chi squared the data must (3 things):
Be discontinuous categories only e.g. phenotypes.
Have a large sample size with no zeros in the counts.
Not be % or ratios ‐ raw counts only.
How is a gene locus described if it has 3 or more alleles?
Give an example
Having multiple alleles
ABO blood groups
Define co-dominance
Where both alleles present in a heterozygote contribute to the phenotype. The phenotype of a homozygote and heterozygote is different.
Define sex linkage
When a gene is present on one of the sex chromosomes