Biology final

What does the law of segregation state?

Organisms inherit two copies of each gene, one from each parent and organisms only donate one copy of each gene in their gametes. Thus, the two copies of each gene segregate, or separate, during gamete formation.

What does Mendel’s law of independent assortment state?

allele pairs separate independtly of each other during gamete formation, or meiosis

What are autosomes?

chromosomes that contain genes for characteristics not directly related to the sex of an organism

If two parents are heterozygous for brown eyes, and they have children; what is the phenotypic ratio of the children? (Brown eyes are dominant to Blue eyes)

3 brown eyes 1 blue

In order for a person to have a recessive disorder, what must their genotype be?

homozygous recessive

If two parents, heterozygous for a recessive disorder, mate and have children, what is the genotype of the offspring who will have the disorder? What is the phenotypic ratio of unaffected to affected offspring?

two lowercase letters, 3:1

If two parents have the genotype Gg for a genetic disorder caused by a dominant allele, what are the chances their children will inherit the disorder?

3/4 or 75%

When Gregor Mendel crossed true-breeding tall plants with true-breeding short plants, all the offspring were tall. Why?

Because the trait of being tall was dominant to the trait of being short plus the parent plants were heterozygous containing the allele of being tall.

What are the sex chromosomes for a female? A male?

female: xx male: xy

A female is born with attached earlobes, which is a recessive phenotype. What are the possible genotypes of her parents?

Ee and Ee, ee and ee, Ee and ee

Typically, how many chromosomes are in the human karyotype?

46

What are some of the things shown on a karyotype?

changes in chromosomes, location of a gene on a chromosome, birth defects (down syndrome)

What is a multiple allele trait? Give an example.

traits controlled by one gene with more than two alleles, blood type

What is a polygenic trait? Give an example.

traits produced by two or more genes, example is human skin color

What are the possible genotypes and phenotypes of blood type?

Phenotypes: A, B, AB, and O

Genotypes: IAIA or IAi, IBIB or Ibi, IAIB, ii

What is an epistatic gene?

Gene that can interfere with the expression of other genes.

What is incomplete dominance? Give an example.

when a heterozygous phenotype is somewhere between the two homozygous phenotypes

example: cross between homozygous red and white flowers have pink offspring flowers

What is codominance? Give an example.

when both traits are fully and separately expressed

example: cross between homozygous red and white flowers have offspring that have spots of red and white

A cross of a red cow (IRIR) with a white bull (IWIW) produces all roan offspring (IRIW). This type of inheritance is known as what?

codominance

What is crossing over and when does it occur in Meiosis?

The exchange of genes, prophase 1

What is gene linkage?

when genes are so close on a chromosome that they are segregated and inherited together

What is epigenetics?

the study of the changes in an organism caused by the modification of the gene expression rather than the alteration of the actual genetic code itself

Where are sex-linked genes located?

in the sex chromosome

Why is colorblindness more common in males than females?

Since it is a recessive disorder, it makes it harder for females to get it because males have only one x and females have two, males only need it on their x, females need it on both

For a female to have a recessive sex-linked trait, what must her genotype be?

X (lowercase letter) X (lowercase letter)

In a pedigree, what does a shaded circle indicate? A half-shaded circle?

Shaded circle means they have the disorder, half-shaded means they are a carrier

Can males be carriers of a recessive disorder? Of a sex-linked trait? Explain.

No, because if the disorder is on the x (they only have one) that means they automatically have the trait or disorder and can’t carry it since they do not have another x to mask it out

How can you tell if a pedigree is for an autosomal recessive trait, rather than an autosomal dominant trait?

If it is recessive both parents will not have the disorder, but offspring can, skips generations, but if it is dominant at least one of the parents have to be affected and no generations are skipped

What are the three parts of a nucleotide?

phosphate group, deoxyribose sugar molecule, nitrogen containing base,

What is the difference between hydrogen bonds and covalent bonds?

a hydrogen bond is an attraction between a slightly positive hydrogen atom to a slightly negative atom and a covalent bond is chemical bond formed when two atoms share one or more pairs of electrons

What are the base-pairing rules?

A to T and C to G

How is DNA different from RNA?

DNA contains deoxyribose and RNA contains ribose

What are the functions of mRNA, tRNA and rRNA?

mRNA: messenger, message translated to form a protein

tRNA: transfer, carries the amino acids during protein synthesis form the cytoplasm to the ribosome

rRNA: ribosomal, forms part of ribosomes, a cell’s protein factories

Explain the process of transcription. Where does it take place?

process of copying a sequence of DNA to produce a complementary strand of RNA, occurs in the nucleus


1. transcription complex recognizes the start site and begins to unwind the segement of DNA
2. forms base pairs, G with C and A with U(T), RNA polymerase moves along the DNA, closes back together
3. the completed strand of RNA separates from the DNA templete, transcription complex falls apart

Explain all the steps of translation. Where does it take place?

process that converts, or translates, an mRNA message into a polypeptide, ocurrs in the cytoplasm


1. exposed codon attracts complementary tRNA bearing an amino acid, pairs with mRNA codon, brings it very close together
2. ribosome forms a peptide bond between the two amino acids and breaks the bond between the first tRNA and its amino acid
3. ribosome pulls mRNA strand the length of one codon, first tRNA shifts into exit site to recharge, first site is empty again exposing next mRNA codon

What is genetic engineering?

changing of an organism’s DNA to give the organism new traits

What are restriction enzymes? Where do they come from?

enzymes that cut DNA moelcules at specific nucleotide sequences, they come from bacteria

What is PCR?

polymerase chain reaction, technique that produces millions or billions of copies of a specific DNA sequence in just a few hours

What is gel electrophoresis? How does it separate DNA fragments?

when an electrical current is used to separate a mixture of DNA fragements from each other, does this by a current pulling them through the gel DNA is negatively charged making it attracted to the posivtive on the other end, lengths are determined by restriction maps (smaller move faster, larger slower) and the restrction enzyms cut it

What do the bands on a restriction map represent? Which pieces of DNA are larger, smaller?

the lengths of DNA fragments between restriction sites in a strand of DNA, larger stay closer to where the start (negative) smaller are closer to where they end up (positive)

Who is the Daddy?

3

What is a clone?

genetically identical copy of a gene or of an organism

What is a plasmid?

closed loops of DNA that are separate from the bacterial chromosome and that repicate on their own within the cell

What is a transgenic organism? How is it produced?

has one or more genes from another organism inserted into its genome, produced by recombinant DNA technology

What is recombinant DNA?

DNA that that contains genes from more than one organism

The restriction site of a restriction enzyme is 

Show where the enzyme cuts the DNA below. How many pieces of DNA result from the cuts?

A T C G A A T T C G C C A T G C C A G A A T T C C C C

T A G C T T A A G C G G T A C G G T C T T A A G G G G

3

Who was Charles Darwin?  Explain his studies on the Galapagos Islands.

a famous biologist, studied the idea of evolution and found that many organisms are able to adapt on the islands

What is variation?

the difference in the physical traits of an individual from those of other individuals in the group to which it belongs

What is adaptation?

a feature that allows an organism to better survive in it environment

What is Natural Selection? What does it act directly on?

a mechanism by which individuals that have inherited beneficial adaptations produce more offpsing on average than do other individuals

What is a population?

all the individuals of a species that live in an area

Overproduction –

Descent with modification –

overproduction: while having many offpsring raises the chance that some will survive, it also results in competition between offspring for resources

decent with modification: natural selection will result in species with adaptations that are well suited for survival and reproduction, more will have the trait in every following generation

What are homologous structures?  What do they tell us about evolution?

features that are similar in structure but appear in different organisms and have different functions, tells us that organisms share a common ancestor

 Explain analogous structures.

structures that perform a similar function, but are not similar in origin like a bat wing and butterfly wing

What is a vestigial structure and how does that show evidence of evolution?   Give an example.

are remnants of organs or structures that had a function in an early ancestor, example is the wings of an ostrich (don’t fly) shows that maybe they once did fly

What is the founder effect?

genetic drift that occurs after a small number of individuals colonize a new area

What is the importance of genetic variation in a population’s gene pool?

allows species to adapt to future environmental changes

 What are the sources of genetic variation?  List and describe their importance.

mutations: random change in the DNA of a gene, which forms a new allele, could be a better feature for the organism and their environment

recombination: new allele combinations form in offspring, alleles are arranged in new ways, happens during meiosis

What is gene flow?  Does it increase/decrease genetic variation?

the movement of alleles from one population to another, increases genetic variation

What is genetic drift?  Does it increase/decrease genetic variation?

changes in the allele frequencies due to chance, decreases genetic variation

What does it mean to be the *same* species?

they are able to mate and reproduce fertile offspring

What is speciation?

the rise of two or more species from one existing species

What does it mean to be reproductively isolated?

occurs when members of different populations can no longer mate successfully with one another

List and describe the 3 types of isolation that lead to reproductive isolation.

behavorial isolation: differences in courtship or mating behaviors

geographic isloation: involves physical barriers that divide a population into two or more groups

temporal isolation: exists when timing prevents reproduction between populations

What is convergent evolution?  Give an example.

evolution toward similar characteristics in unrelated species, dolphins (mammals) and sharks (fish), similar tail fins

What is divergent evolution?

when closely related species evolve in different directions that become increasingly different, kit fox and a red fox grew up in differnt environments, but have a common ancestor

What is coevolution?  Give an example.

the process in which two or more species evolve in response to changes in each other

What does a mutation affect?

a mutation affects the DNA in the gene

What is a half-life?

the amount of time it takes for half of the isotope in a sample to decay into a different element, or its product isotope

Explain how radiometric decay is used to determine the age of a fossil.

uses the natural decay rate of unstable isotopes found in materials (fossils)

Chlorine-36 decays to Argon-36 and the half-life is 300,000 years. How old would a fossil be after:

·         One half-life?

·         Two half-lives?

·         Three half-lives?

150,000

75,000

37, 500

When do we theorize the 1st cells appeared on earth?

3\.8 billion years ago, or 750 million years ago

What theory explains Eukaryotic cell development?

endosymbiotic theory

What is the difference between niche and habitat?

a niche is composed of all of the physical, chemical, and biological factors that a species needs to survive, stay healthy, and reproduce an a habitat is all of the abiotic and biotic factors in the area in which an organism lives

What is the difference between a food chain and a food web?

a food chain is a sequence that links species by their feeding relationships and a food web is a model that shows the complex network of feeding relationships and the flow of energy within and sometimes beyond an ecosystem

What are the trophic levels in a community?

producer, primary consumer, secondary consumer, tertiary consumer

How much energy is transferred between trophic levels, how much energy is lost as heat?

10 percent is transferred, 90 percent is lost

What is a keystone species?

species that has an unusually large effect on its ecosystem

What is ecological equivalence?

species that occupy similar niches but live in different geographical regions

What is niche partitioning?

example: two squirrels live in the same tree but one eats nuts from the ground, but one eats nuts from the top of the tree (niche is divided)

What is competitive exclusion?

states that when two species are competiting for the same resources, one species will be better suited for the niche, and the other species will be pushed into another niche or become extinct

What is succession?

the sequence of biotic changes that regenerate a damaged community or create a community in a previously uninhabited area

What is the difference between primary succession and secondary succession?

primary: the establishment and development of an ecosystem in an area that was previosuly uninhabited

secondary: the reestablishment of a damaged ecosystem in an area where the soil was left intact

What are the three types of symbiosis?

commensalism, mutualism, parasitism

What impact do births, deaths, immigration, emigration have on a population?

they determine the populations growth rate and capacity

Explain clumped, uniform, and random dispersion of a population.

clumped: live close in groups for mating, protection, access to food and resources

uniform: competition for limited resources lead to individuals living at specific distances from each other

random: they are spread randomly withing an area or volume

What are the conditions for exponential growth of a population?

when resources are abundant

What are the conditions for logistic growth of a population?

when resources are limited

What is carrying capacity?

the maximum number of individuals of a particular species that the environment can normally and consistently support

What has increased Earth’s carrying capacity?

migration, agriculture, medical advances, and communication, technology

What are density-dependent limiting factors for population growth?

limiting factors that are affected by the number of individuals in a given area

What are density-independent limiting factors for population growth?

the aspects if the environment that limit a population’s growth regardless of the density of the population

How is an ecosystem impacted by loss of biodiversity?

lowers an ecosystem’s productivity and energy levels, it reduces the ecosystem’s stability and makes it more difficult for the ecosysem to handle future change

What is a renewable resource? Nonrenewable resource?

Renewable: resources that cannot be used up or can replenish themselves overtime

Nonrenewable: used faster than they form

What leads to biomagnification?

when toxic chemicals are consumed indirectly by organisms through food

What is an umbrella species?

its protection means a wide range of other species will also be protected

What is an indicator species?

species that provides a sign or indication of the quality of the ecosystem’s environmental conditions

What is an invasive species? Give two examples.

species that can harm an environment take over, reproduce quickly, parasite and burmese python

What are the different types of pollution?

air, water, and land

What are the main greenhouse gases?

carbon dioxide, methane, and water