Fucking Bio 11 Exam

Mitosis

cell division that results in two identical daughter cells

Meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

True breeding

organisms that exhibit the same traits, generation after generation

What plant did Mendel study?

pea plants

Cross breeding

combining gametes from parents with different traits. Selectively fertilizing a female gamete with a specific male gamete.

Parental/P Generation

Organisms initially crossed in breeding and are typically true breeding

F1 Generation

The offspring of a cross of the P generation

Monohybrid crossing

A cross of 2 individuals that differ by one trait Ex. Black and white mice

F2 generation

the offspring of a cross between the F1 generation

Why would traits disappear in the first gen but reappear in the second?

When crossing true breeds of white and purple plants (both of which are homozygous), they'll become heterozygous and therefore the colour of the dominant allele. If all resulting gametes are heterozygous, then this must be true and they'll all be purple. However, by the second gen, there's a chance of homozygous recessive plants if two recessive alleles meet. Therefore, this trait will reappear.

Dominant allele

Describes a trait that covers over, or dominates, another form of that trait.

recesive allele

An allele whose trait is hidden or masked when a dominant allele is present --\> must have 2

Law of Segregation

Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair (parent) is present in each gamete

Genotype

The combination of alleles for any given trait. The organism's entire genetic make-up (Aa, AA, aa)

Phenotype

An organism's physical appearance, or visible traits.

Homozygous

An organism that has two identical alleles of a gene (for a trait)

Heterozygous

An organism that has two different alleles (of a gene) for a trait

Test cross

the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

Punnett Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

Incomplete dominance (with example)

Neither allele for a gene completely conceals the presence of the other. It's more of a mix between the two, for example, pink flower colour from red and white.

Codominance (with example)

Both traits (alleles) are equally expressed in a heterozygote; both are dominant. An example is a spotted cow. A common example is blood type.

continous variation (with examples)

a range of variation in one trait resulting from the activity of many genes. Ex. Height, skin, weight, ear length (corn), kernel colour (wheat).

Polygenic trait (with examples)

A trait controlled by two or more genes. Ex, Skin colour. Each dominant allele contributes to trait, but recessive don't.

sex-linked

A trait controlled by a gene on a sex chromosome (X or Y)

What organism was chosen to study sex-linked inheritance

Fruit flies

Why were fruit flies chosen for Morgan's research?

Rapid reproduction, economical to maintain, easy traits to characterize.

Epistasis (with example)

When one gene masks another. Ex. fur colour in mice. Whether there's pigment or not and how much there is.

Pleiotropy (with example)

One gene that affects multiple phenotypic characters (traits). Ex. dwarfism (achondroplasia) or gigantism (acromegaly)

X-inactivation

one x chromosome becomes inactivated during embryonic development.

Environmental effects

Hydrangea colour influenced by soil pH, skin colour by genetics and environmental conditions, and coat colour in arctic foxes influenced by heat sensitive alleles.

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family. --\> A chart or "family tree" that tracks which members of a family have a particular trait

How are females on pedigrees represented

Circles

How are males on pedigrees represented

Squares

Half-filled on pedigree

heterozygous or carrier

autosomal inheritance

Inheritance of a genetic trait not on a sex chromosome

autosomal dominant

the inheritance of a dominant phenotype whose gene is on an autosomal chromosome

autosomal recessive

the inheritance of a recessive phenotype whose gene is on an autosomal chromosome

Evidence for evolution

1. Fossil record

2. anatomy

3. biogeography

4. embryology

5. DNA relationships

Fossil record

the remains and traces of past life that are found in sedimentary rock; it reveals the history of life on Earth and the kinds of organisms that were alive in the past.

Evidence from the fossil record

1. Fossils found in young layers of rock are more similar to current species than those in older, deeper rock.

2. Fossils appear in chronological order in rock layers.

3. Not all organisms appear in the fossil record at the same time.

Transitional fossil (with example)

Fossils that show intermediary links between groups of organisms and shares characteristics common to 2 now separate groups . Ex. fossilized whales that link present-day whales to terrestrial ancestors.

vestigial structure (with examples)

A structure that is a reduced version of a structure that was functional in the organism's ancestors. Ex. human tail bones, pelvic bones in whales

Biogeography (with example)

The study of the past and present geographical distribution of species populations. ex. Many observations Darwin and Wallace made were based on this. They hypothesized that species evolve in one location and then spread to others.

How biogeography supports evolution (with examples)

1. Geographically close environments (ex., desert and forest habitats in South America) are more likely to be populated by related species than those geographically separated yet environmentally similar. Ex. Cacti are found in geographically close deserts but not in all deserts around the world.

2. Animals found on islands often closely resemble those found on the closest continent. Suggests evolution from mainland migrants and descendants adapting to new environments. Ex. lizards found on Canary island, off northwest coast of Africa closely resemble those found in west Africa.

3. Fossils from same species are found on coastline of neighboring continents.

4. Closely related species are almost never found in exactly the same location or habitat.

homologous structure (with example)

Structures with similar structural elements and origin but serve different functions. Ex., human forearm bone, frog arm bone, bat wing bones, etc.

analogous structure (with example)

Structures of organisms that perform similar functions yet have no common evolutionary origin/connection. ex. insect and bird wings

What type of evidence are analogous and homologous strucures?

Evidence from anatomy

Embryology (with examples)

The study of early, pre-birth stages of an organism's development. Embryos of different organisms exhibit similar stages of embryonic development. Ex., all vertebrate embryos have paired pouches of the throat. In fish and some amphibians, these become gills. At certain stages, similarities become more apparent than differences. This points to a common ancestral origin.

Evidence from DNA (with examples)

The more genes and genetic sequences two individuals have in common, the more closely related they are. Evolutionary relationships between species are reflected in DNA. Similar patterns in DNA indicates close connections and a similar ancestor. EX. dogs are related to bears and whales and dolphins are related to ungulates (hoofed animals).

What happens when allele frequencies change?

Changing percentages, or frequencies, of alleles within populations are the small events that lead to evolution within a population, or microevolution.

allele frequency

Number of times that an allele occurs in a gene pool compared with the number of alleles in that pool for the same gene

5 factors of microevolution --\> changes in allele frequencies

1. Mutation

2. Gene flow

3. Non-random mating

4. Genetic drift

5. Natural selection

Mutations (with example)

A change that occurs in an individual's DNA. Heritable mutations can potentially impact entire gene pools. They randomly introduce new alleles into populations, changing allele frequencies. Ex. poison resistance in Norway rats is a selective advantage. Few rats developed a resistance to Warfarin (used to control rat populations) and survived, mated, and passed on this mutation.

Gene flow (with example)

The net movement of alleles from one population to another because of individual migration. Ex. greys wolves have large territories and a lone wold can travel a very far distance to mate. Often, they mate with a member of a nearby population, bringing new alleles into the gene pool of said population. This genetic diversity could help the population survive.

Non-random mating (with example)

Mating among individuals on the basis of mate selection for a particular phenotype or due to inbreeding. Basically, an organism deciding who to mate with based on physical or behavioural traits. Ex. Bluefooted boobies choose mating partners based on a dance and how blue the feet are.

Non-random mating (inbreeding)

When closely related individuals breed. Close relatives share similar genotypes, so inbreeding increases the frequency of homozygous genotypes. Recessive alleles are more likely to be expressed.

Genetic drift

The change in frequencies of alleles because of chance events in a breeding population. In smaller populations, frequencies of certain alleles can be changed by chance. The smaller the population, the less likely that the parent gene pool will be reflected in the next generation. In larger populations, there is a better change of this in future generations.

Genetic drift examples

1. The founder effect

2. the bottleneck effect

The founder effect (with example)

a change in a gene pool that occurs when a few individuals start a new isolated population. This occurs frequently on islands. ex. strong winds can carry a single, pregnant fruit fly to a previously unpopulated island, where the fruitfly and her offspring can found a new colony.

The bottleneck effect (with example)

Changes in gene distribution that result from a rapid decrease in population size. Ex. an ant colony getting run over by a scooter, only a selective and random few survive.

Hardy-Weinberg equation (use and equation)

Provides a simple mathematical model of genetic equilibrium in a gene pool. It's mainly used to calculate allele and genotype frequencies in populations, usually to study changes and measuring their rates.

(p + q)^2 \= p^2 + 2pq + q^2

p

frequency of dominant allele

q

frequency of recessive allele

p^2

frequency of homozygous dominant genotype

q^2

frequency of homozygous recessive genotype

2pq

frequency of heterozygous genotype

How to solve Hardy Weinberg problems

1. See what's given and needed

2. Find out p or q to find all other values

3. Take the square root of q^2 to find q

4. Find p by subtracting q from 1

5. Find p^2 by multiplying it by itself

6. Find 2pq by multiplying p by q by 2

7. Check by adding up p^2 + 2pq + q^2. This should equal 1 or 100%

Speciation

the formation of new species from existing species

Biological species definition

a population or group of populations in nature whose individual members can interbreed to produce viable, fertile offspring.

What are the 2 reproductive isolating mechanisms preventing gene flow between populations --\> leading to speciation?

1. Pre-zygotic barriers

2. Post-zygotic barriers

Pre-zygotic isolating mechanism

a barrier that either impedes mating between species or prevents fertilization of the eggs if individuals from different species attempt to mate; also called pre-fertilization barrier

Examples of pre-zygotic isolating mechanisms

1. behavioural isolating mechanisms

2. habitat isolating mechanisms

3. Temporal isolating mechanisms

4. mechanical isolating mechanisms

5. gametic isolating mechanisms

Behavioural isolating mechanism (with examples)

Special signals or behaviours that are species-specific and prevent interbreeding with closely related species. Unique isolating behavioural patterns or rituals. ex. courtship rituals or mating calls

Habitat (ecological) isolating mechanism (with example)

Two species that live in the same region but are separated by habitats, and therefore speciate. They encounter each other rarely, if at all. Ex. 2 species of garter snake where one prefers water and the other is terrestrial