Exam 2 Flashcards
chromosomes
structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes
genes/genetics
Gene- a piece of DNA that codes for a product (usually a protein)
Genetics- the study of life
alleles/dominant and recessive
variant of a gene
- Dominant alleles only need one copy present, recessive alleles need two copies of the allele
mitosis
a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus
meiosis
a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.
random alignment
chromosomes during metaphase I allows equal opportunity for a particular chromosome to migrate into a cell. This type of independent assortment gives rise to exponential gene combinations in the offspring
crossing-over
the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring
x and y chromosomes
x= female y= male
co-dominance of ABO blood groups
possibility for the above couple to have a baby with type A blood? 50%
possibility for the couple to have a baby with type O blood? 0%
Use the ABO alleles for blood type to demonstrate the following genotypes:
-heterozygous: AB or AO or BO
-homozygous dominant: AA or BB
-homozygous recessive: OO
-co-dominant: AB
mutations
errors in copying genes/chromosomes
pleiotropic traits
gene has multiple effects on phenotype (i.e. testosterone )
polygenic traits
determined by effects of two or more genes (i.e. eye color and height)
detrimental alleles
An allele that results in a lower fitness than an allele which instead is designated as neutral or beneficial.
sex-linked traits
a gene is found only on the X chromosome and not the Y chromosome, it is said to be a sex-linked trait. Because the gene controlling the trait is located on the sex chromosome, sex linkage is linked to the gender of the individual
hemophilia
• Hemophilia A – - Sex linked on X chromosome - Most common in males (1 in 10,000 in males 1 in 100,000,000 for females) • Hemophilia B – - Sex linked on X chromosome - Most common in males (same stats as A) • Hemophilia C – - Non sex linked - Occurs in males and females
heterozygous carrier
Heterozygous means that an organism has two different alleles of a gene
Carriers are always heterozygous
example of biological evolution
The definition of biological evolution is: change in allele frequency in a population from one generation to the next.
Who? A population
What? The allele frequencies in that population
When? Over the time of a generation, which is the length of time it take for a group of individuals in this species to grow up and have offspring
Why? different species live for different lengths of time, and so generation lengths differ
forces of evolution
- natural selection- process by which the best-adapted individuals produce the most offspring. NOT RANDOM
- genetic drift- random process in which chance plays a role in deciding which gene variants (alleles) survive RANDOM
- gene flow- occurs when genes are carried from one population to another CREATES NEW VARIATION
- mutation- also random
natural selection
competition- food, water, shelter, mates
variation- traits of a population
Direction Selection
one of the extremes in the population is more successful than the other extreme i.e. - Predator-Prey co-evolution
Stabilizing Selection
selections against both extremes and selection for the average (i.e. human babies)
Disruptive Selection
selection for the extreme and against the average
Balanced Polymorphism
when individuals having a heterozygous genotype having greater reproductive fitness than those with homozygous genotypes. So selection for multiple alleles (i.e. Sickle-cell anemia and malaria)
point mutation
a mutation affecting only one or very few nucleotides in a gene sequence
chromosomal mutations
A chromosome anomaly, abnormality, aberration, or mutation is a missing, extra, or irregular portion of chromosomal DNA. It can be from an atypical number of chromosomes or a structural abnormality in one or more chromosomes
gene flow
the spread of a gene through out a population
gene flow barriers are things like
-water (ocean)
think of the flowers around the great wall of China
genetic drift
variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.
i.e. the flowers around the great wall of china are experiencing this
Founders effect
the reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors.
think of midgets in Amish society
