Sciece Exam 😩 Flashcards
Genotype
Genetic constitution of something
Phenotype
Traits or physical appearance
Allele
Different versions of a gene in a population
Gene
Unit of heredity transferred from parent to offspring
Heterozygous
One dominant and one recessive allele (Bb)
Homozygous dominant
Two dominant alleles (BB)
Homozygous recessive
Two recessive alleles (bb)
Homologous pairs
Two chromosomes, one from each parent, that form a pair of
What are two examples of how environment influences phenotype
- Siamese kittens born white, dark coloration in cooler areas over time (color pointing)
- Hydrangea flowers change color in different soils (blue in acidic, pink in basic/neutral)
What are karyotypes
A complete set of chromosome that can be used to determine if a persons chromosomal make up is normal or abnormal
How is meiosis different from mitosis
Mitosis—produces 2 identical cells with same number of chromosomes, one diploid cell into two diploid cells, all body/somatic cells except gametes
Meiosis—produces 4 unique cells with 1/2 of the chromosomes of original cell, one diploid cell into four haploid cells, gametes, sex cells, pollen, etc
What is meiosis
Cell division process of gametes and sex cells that produces four unique haploid cells
What are the steps of meiosis
- Start with one chromosome from mom and one from dad (a chromosome pair)
- Chromosome duplicate (DNA doubles)
- Chromosomes line up
- Chromosomes split
- Pairs split apart again, each haploid cell has 1/2 original DNA, gametes form
What are haploid cells
Contains one copy of each chromosome
Diploid
Contains two copies of each chromosome
Why is meiosis important in reproduction/long term survival of species
Sexual reproduction produces more variation in a population which can help the species adapt and ensure a better change of survival
What is the formation of sperm called
Spermatogenesis
What is the formation of eggs called
Oogenesis
Pollen
Contains male reproductive cells
Anther
Produces pollen
Filament
Stem like, holds anther on top
Stamen
Filament and anther
Ovary
Holds eggs
Ovules
Produce egg cells
Style
Extension of ovary
Stigma
Tip of style, pollen must land here for reproduction to occur
Pollen tube
forms when pollen meets stigma, pollen tube enters ovary and fertilizes egg in ovule
Pistil
Ovary, style, stigma, and ovules
Incomplete dominance
The action of one allele does not completely mask the action of another, traits are mixed together (red flower + white flower = pink flower)
Codominance
Both alleles contribute to the phenotype/are equally expressed, not mixed (roan cow = red and white fur)
Simple/complete dominance
One allele exerts greater influence over the other
Multiple alleles
When there are more than two alleles for a gene in a population
Pleiotrophy
When one gene affects multiple traits
Polygenic inheritance
When a trait is controlled by the interaction of multiple alleles
Lethal alleles
An allele that results in the death of an individual that carries it
Mendelian traits
Traits that follow Mandels rules (segregation, independent assortment, dominance)
Non Mendelian traits
Traits that don’t follow mendels laws (codominance, incomplete dominance, multiple alleles, etc)
How can you tell if a trait on a pedigree is dominant
One parent must have the trait, usually don’t skip a generation,
How can you tell if a trait on a pedigree is recessive
Parents don’t have to show it, can skip generations
How can you tell if a trait on a pedigree is autosomal
Males and females have it in roughly equal proportions, male to male transmission
How can you tell if a trait in a pedigree is sex linked
Less gender equality between who gets it, more affected malea
Polygenic traits
Trait that is influenced by two or more genes
Epistasis
When one allele eliminates the expression of another, substituting it’s own phenotype
