Genetics and Evolution Flashcards
Homozygous
Describes a fertilized egg that receives the same allele from each parent for a particular trait
Allele
An allele is an alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome. These DNA codings determine distinct traits that can be passed on from parents to offspring.
Heterozygous
Describes a fertilized egg that receives a different allele from each parent for the same trait
Gene
portion or portions of the DNA molecule that code for proteins that shape phenotypic traits
Chromosomes
Sets of paired bodies in the nucleus of cells that are made of DNA and contain the hereditary genetic information that organisms pass on to their offspring. Humans have 46
Mitosis
The way body cells make copies of themselves. The pairs of chromosomes in the nucleus of the cell duplicate and line up along the center of the cell. The cell then divides, each daughter cell taking one full set of paired chromosomes.
Meiosis
The way sex cells make copies of themselves, which begins like mitosis, with chromosomes duplication and the formation of two daughter cells. However, each daughter cell then divides again without chromosome duplication and, as a result, contains only a single set of chromosomes rather than the paired set typical of body cells.
Locus
A portion of the DNA strand responsible for encoding specific parts of a organisms biological makeup
Linkage
An inheritance pattern in which unrelated phenotypic traits regularly occur together because the genes responsible for those occurring traits are passed on together on the same chromosome.
Crossing over
The phenomenon that occurs when a part of one chromosome breaks off and reattaches itself to a different chromosome during meiosis also called incomplete linkage.
Genotype
Tells what the type is
Phenotype
Shows the trait
Pan-genesis
A theory of hereditary suggesting that an organisms physical traits are passed on from one generation to the next in the form of multiple distinct particles given off by all the parts of the organism, different proportions of which get passed on to the offspring via sperm or egg
Polygeny
The phenomenon whereby many genes are responsible for producing a phenotypic trait, such as skin color
Continuous variation
A pattern of variation involving polygeny in which phenotypic traits grade imperceptibly from one member of the population to another without sharp breaks
Pleiotropy
The phenomenon whereby a single gene may affect more than one phenotypic trait
Mutation
The creation of a new allele for a gene when the portion of the DNA molecule to which it corresponds is suddenly altered
DNA
The structure that carries the genetic heritage of an organism as a kind of blueprint for the organisms construction and development
Genome
The sum total of all the genetic information about an organism, carried on the chromosomes in the cell nucleus
RNA
Controls how information is used
Single stranded
Uracil - one of the four nucleobases in the nucleic acid of RNA that are represented by the letters A, G, C and U.
Ribose
Dominant Allele
Traits that mask the presence of other traits
Recessive Allele
The masked trait
Punnett Square
named after Reginald C. Punnett, who devised the approach, and is used by biologists to determine the probability of an offspring’s having a particular genotype.
Gregor Mendell
Priest in Brno (Chech Republic) 29 got college degree. the founder of the new science of genetics. Mendel demonstrated that the inheritance of certain traits in pea plants follows particular patterns, now referred to as the laws of Mendelian inheritance
Polygenetic traits
Reflects the activities of more than one gene Continuous variation Examples: Fingerprints eye color hieght skin color
Heritability
the proportion of observable differences in a trait between individuals within a population that is due to genetic differences.
Y Chromosome
Can trace male ancestry
Has few genes
Specific mutations can be used to group related males together in to haplotypes, die out in two generations
Mitochondrial DNA
Can trace female ancestry through it
Population Genetics
Developed in early 20th Century
Linked to Darwinian evolution and Mandellian inheritance. Looks at distribution of genetic alleles and genotypes across space and time. How do frequency of alleles change.
Allele Frequency
the frequency of an Allele in a population
Heterozygosity
Expected proportion of heterozygotes in the population vs actual. Tells us how diverse a population is.
Hardy-Weinberg
(p+q)^2=1
Measures the change in allele frequency from one generation to another. states that both allele and genotype frequencies in a population remain constant—that is, they are in equilibrium—from generation to generation unless specific disturbing influences are introduced.
Four forces of evolution
Mutation
Gene flow
Genetic drift
Natural selection
Mutation types
Point - the replacement of a single base nucleotide with another nucleotide of the genetic material, DNA or RNA
Deletion - part of a chromosome or a sequence of DNA is missing. Deletion is the loss of genetic material
Insertion - addition of one or more nucleotide base pairs into a DNA sequence
FST
The proportion of total variation that can be accounted for by between population differences
Bottleneck
An event where a large portion of the population is prevented from reproducing
Founders Affect
Allele frequencies in a small group of founders may be different (by chance) from their original population
Natural Selection
where an organism best suited for an environment survives and passes on its genes
Assortative Mating
where individuals with similar genotypes and/or phenotypes mate with one another more frequently than what would be expected. Doesn’t change the allele frequency but does increase homozygous individuals
Dissortative Mating
Where opposites mate.
