exam 2 Lecture 7-8 Flashcards
Genes definition
Made of DNA
DNA forms what?
Double-stranded helix
Define Chromosomes
Made of many genes and intergenic DNA that lies between the genes
Genomes are made up of what?
Several chromosomes
Where is the Genome found?
The nucleus
Define Homologous Chromosomes?
Pairs of chromosomes that have the same genes in the same order with slight variation
Define Diploid
Two of each HOMOLOGOUS chromosomes ( 1 from mom 1 from dad)
Diploid cells are found in what cell?
ALL somatic cells
Define haploid cells?
One copy of each homologous chromosomes.
Define Meiosis and what it produces? examples?
Type of cell division. produces haploid gametes from diploid germlines
EX: Sperm + Egg, Pollen + Ovules
Meiosis is requirement for what?
Sexual reproduction
In a question about cell division what does the variable n refer to?
The number of different types of homologous chromosomes.
Broad steps for meiosis
1.) Interphase
2.) Meiosis 1
3.) meiosis 3
define interphase
Each chromosome is replicated to produce two sister chromatids
Define chromatid
one parental strand and one synthesized DNA strand each
What happens in Meiosis 1?
Homologous chromosomes seperate.
What happens in meiosis 2?
Sister chromatids separate.
Define centeromere
a constricted region of a chromosome
Define tetrad
Pair of homologous chromosome, composed of two sister chromatids each connected at the centromere
Define Spindle fibers( and what structure is it?)
Protein structures that attach the kinetochore to centrosome
Define kinetochore ( and what complex is it?)
Protein complex that forms at the centromere
Define centrosome?
Small organelle like structure with TWO centrioles
Define Allele? How did it originate?
Different version of the same gene.
Originated from a mutation
Define zygote
Diploid single-celled first stage of a diploid multicellular organisms existence
What does mitosis produce?
Multicellular complex organisms from a simple zygote
Define phenotype
Observable trait of an organism
Define Dominate Phenotype
The phenotype that is seen in an offspring when true breeding
Define Recessive phenotype
The phenotype that is typically not seen in offspring when true breeding ( unless you get rr )
Define Discrete phenotype
They do not blend. You will see BOTH phenotypes
Define Genotype
Combination of alleles in a genome
Define Homozygous Genotype
2 alleles in the genome are IDENTICAL
Define Heterozygous genotype
2 alleles in the genomes are DIFFERENT
Define species
a group of INDIVIDUAL organisms that interbreed and reproduce
Individuals of a single species display what? Example; think of dog breeds
Extreme phenotypic differnces.
Two different species can exhibit what? and give example.
Similarities
example: African fish eagle and bald eagle… look the same but two different species
Define reproductive barriers
and list two examples
Separates species.
-Prezygotic barrier
-Postzygotic barrier
Prezygotic barrier and example.
Mechanism that prevents zygote formation.
example; F. heteroclitus Females prefer F. heteroclitus males
Postzygotic barriers and example.
A mechanisms that occurs after zygote formation
example; LOW developmental success of hybrids produces by F. heteroclitus females.
How do species form?
Speciation!
Define speciation
Formation of two species from one original species.
Define allopatric speciation with examples
Involves geographic separation of populations from a parent species and subsequent evolution.
example; Hawaiian honeycreepers and honeycreepers
Define sympatric speciation
speciation within the same space
Define population genetics
Study of how evolutionary forces shape allele frequencies and genotype frequencies in a population.
Define Gene pool
sum of ALL allele in the population.
Define allele frequency
rate at which a specific allele appears w/in a population
Define Genotype frequency
rate at which a specific genotype appears w/in a population
What does the Hardy-Weinberg equilibrium state?
Population allele and genotype frequencies are inherently stable unless some kind of evolutionary force is acting upon the population.
HW-equilibrium equation calculates what?
Allele frequencies can be used to calculate genotype frequencies and vice versa.
Examples of Evolutionary forces for HW-equilibrium equation
Natural selection
Genetic drift
Mutation
Migration
HW equilibrium equation
p^2+ 2pq+q^2=1
