BSC 108 Exam 3 - University of Alabama

What is the structure of a strand of DNA?

double helix, twisted ladder

What is DNA composed of?

nucleotide subunits

What is the backbone of DNA?

deoxyribose and a phosphate group

What is the backbone of DNA covalently bonded to?

nitrogen-containing bases

How many strands of DNA does a DNA molecule contain?

two

The two strands of DNA are:

complementary

What are the nitrogen-containing bases in DNA?

adenine, guanine, thymine, cytosine

How are the nitrogen-containing bases held together?

hydrogen bonds

What bases pair together?

adenine=thymine

guanine=cytosine

How does DNA replicate?

DNA molecule unwinds and each strand is a template for complementary base pairing; each daughter helix contains an intact strand from the parent helix and a newly synthesized strand therefore DNA replication is semiconservative

One parent molecule is composed of two __________________ that separate.

complementary strands

Each strand is used as a ______________ to make a new strand.

template

What are the two daughter molecules composed of?

One "old" (parent) strand and one "new" (synthesized) strand

Where do parent strands separate?

origins of replication

Where and how does synthesis of two new complementary strands occur?

replication bubbles, using the parent strands as templates

What do the replication bubbles do as DNA replication progresses in both directions at the replication forks?

merge

How does an organism's DNA lead to specific traits?

by dictating the synthesis of proteins

What is the structure of RNA?

single-stranded nucleic acid

RNA contains ________ instead of thymine.

Uracil

What sugar is used in RNA?

ribose

What is the function of mRNA (messenger RNA)?

carries the genetic message from a gene (DNA) to ribosomes that translate it into a protein

What is the function of tRNA (transfer RNA)?

translates codons into amino acids

Where does tRNA pair with mRNA?

at the anitcodon

What is the function of rRNA (ribosomal RNA)?

to make up ribosomes with proteins

What two processes do genes code for specific proteins?

transcription and translation

What is transcription?

synthesis of mRNA under the direction of DNA

Where does transcription occur?

nucleus of a cell

What is translation?

synthesis of a polypeptide (which will become a protein) under the direction of mRNA

Where does translation occur?

on the ribosomes in the cytoplasm

What is the structure of tRNA?

three leaf clover, where one loop is the anticodon and the other end is where the amino acid attaches

What is tRNA's role in translation?

picks up amino acids and matches them to codons

How does information flow in a cell?

DNA -> RNA -> Protein

DNA makes RNA through:

transcription

RNA makes protein through:

translation

What is a mutation?

change in the genetic material of a cell

What is a point mutation?

change in one base pair of a gene

What can a point mutation change?

a gene's protein product

What does change in the DNA molecule cause?

altered mRNA to be transcribed and different amino acids to be added to the polypeptide chain

What are frameshift mutations?

mutations caused by insertions/deletions of a number of nucleotides not divisible by 3

What are potential effects of frameshift mutations?

completely different translation, replication ending too soon, too-long chain

What is a plasmid?

small ring of self-replicating DNA separate from the larger chromosome(s)

What is biotechnology?

manipulation of organisms or their parts to produce a useful product

What is recombinant DNA?

molecule containing DNA from two different sources

What is a genetically modified organism (GMO)?

organism that has acquired one or more genes artificially

What is a transgenic organism?

a GMO that has received genes from an organism from another species

What is a restriction enzyme?

bacterial enzyme that cuts foreign DNA at one very specific nucleotide sequence

What is a polymerase chain reaction (PCR)?

technique used to obtain many copies of a DNA molecule

What is a stem cell?

a cell that generates replacements for nondividing differentiated cells

What is an embryonic stem cell?

cells in early animal/human embryo that differentiate during development to create all of the specialized cells in the body

What is gene therapy?

procedure intended to treat disease by altering an afflicted person's genes

What is reproductive cloning?

using a body cell to make one or more genetically identical individuals

What is therapeutic cloning?

reproductive cloning of human cells by nuclear transplantation

How could a scientist genetically engineer an organism?

1. Isolate a bacterial plasmid and DNA of interest from another organism

2. Two are joined together, resulting in recombinant plasmids

3. Recombinant plasmids are mixed with bacteria, which "take up" the recombinant plasmids

4. Each bacterium (carrying the recombinant plasmid) reproduces via cell division to form a clone

a. The foreign gene carried by recombinant plasmid is also copied

5. Transgenic bacteria with the gene of interest can then be grown in large tanks

6. Final product may be:

a. Copies of the gene itself

b. Product of the cloned gene

What are some examples of how genetic engineering has affected agriculture and medicine?

herbicide resistant crops, nutritional value of crops, greater yield of crops by making them resistant to natural destroyers, vaccines, gene therapy

What is DNA fingerprinting?

technique that analyzes an individual's unique collection of genetic markers to determine whether two samples of genetic material came from the same individual

What are some of the common uses of DNA fingerprinting?

to solve crimes using forensics, paternity/maternity testing, family genetics, ancient DNA/archaeology

What did Darwin's observations of the geographic distribution of species like the Galapagos finches lead to?

ideas about adaptation to the environment and origin of new species

What ideas was Darwin influenced by?

gradualism by Hutton and Lyell

What is adaptation?

a characteristic that helps and individual survive and reproduce

What is Darwin's theory of natural selection?

Organisms have variations, struggle to exist, and differ in fitness. Organisms that are more fit will successfully reproduce and pass on desirable variations and in this way, they will become adapted to their environments

What is Darwinian fitness?

contribution to the next generation's gene pool, relative to the average for the population

What is natural selection?

natural differential success in reproduction among individuals that vary in heritable traits (coloration or size)

What is artificial selection?

purposeful breeding of domesticated plants and animals by humans (dog breeding)

What can natural selection do?

increase the adaptation of organisms to their environment over time (camouflage)

_________ evolve over time, not individual ___________

populations; organisms

Natural selection can amplify or diminish only ________ traits, not ________ traits

heritable; acquired

What is descent with modification?

all organisms are related through descent from a common ancestor

these descendants spilled into various habitats over millions of years

accumulated various modifications that fit them to their specific ways of life

How can a trait be favored in one situation but not in another?

environmental factors vary from place to place and time to time

What are the 4 types of evidence supporting the Theory of Evolution?

biogeographical

embryological

fossils

DNA and biochemical evidence

What is biogeographical evidence?

global distribution of organisms and unique features of island species can be evaluated over time

What is embryological evidence?

embryos of two species can have very close resemblance, even if the adult species do not resemble each other

What is fossil evidence?

document differences between past and present organisms

What is DNA and biochemical evidence?

DNA comparisons can show how related species are

Two different species can evolve independently but:

acquire the same traits as adaptations to similar environments

What are homologies (homologous structures)?

similarities among living organisms that are due to shared ancestry

What are analogies (analogous structures)?

similarities among living organisms that are due to similar environmental pressures and natural selection (convergent evolution)

What is speciation?

evolutionary process in which one species splits into two or more species

What is a species?

group of populations whose members possess similar anatomical characteristics and the ability to interbreed

What is a genetic drift?

change in gene pool of a population due to CHANCE

How can new species form without geographic isolation of two populations?

two distinct gene pools emerge through chromosomal changes due to errors in mitosis and meiosis, habitat differentiation, or sexual selection

What is adaptive radiation?

the evolution of diversely adapted species from a common ancestor upon introduction to a new environment

As descendants of a common ancestor spread out into various habitats:

they acquired adaptations to their particular environments through natural selection

What type of adaptations could have come from adaptive radiation?

modifications of the ancestral anatomical structures to suit their new functions (swimming, flying, walking)

What is a community?

a group of populations of different species interacting with another in a single environment

What is an ecosystem?

a community interacting with the physical environment

What is the primary ecological succession?

community arises in a lifeless area with no soil

What is the secondary ecological succession?

community arises in a lifeless area with soil

What is predation?

predator kills and eats prey (humans hunting deer to eat, cat kills and eats mouse)

What is competition?

fight for similar required and limited resources (humans fight for resources, predators fight for prey)

What is parasitism?

parasite benefits, host is harmed (tick, tapeworm, lice, leech)

What is commensalism?

one benefits, other neither benefits nor is harmed (tree frogs use plants as protection, jackals follow tigers and eat their scraps)

What is mutualism?

each benefit from relationship (woodpeckers eat ticks from rhinos' backs, bees pollinate flowers)

What is symbiosis?

a close relationship between two species

What are the three types of symbiotic relationships?

parasitism, commensalism, mutualism

What is included in a species' ecological niche?

its habitat, role in the community, and interactions with other species

What can resource partitioning lead to?

an increase in the chances of survival for species who share a habitat by reducing competition for resources

What is the biosphere?

it encompasses all of the ecosystems on Earth

What is the source of energy for the entire biosphere?

the sun

What is an autotroph?

they can make their own food and sustain themselves (plants)

What are heterotrophs?

they can't make their own food, rely on other organisms/organic products for food (humans)