exam 1 genetics

selective breeding (artificial selection)

the process of developing organisms with specific characteristics as chosen by the breeders

Gregor Mendel (1822-1884)

Amateur botanist who published an explanation of hereditary transmission in plants in 1866. Known for his pea-plant experiments and commonly referred to as the "father of genetics"

modern genetics

the study of heredity and the variation of inherited characteristics

bacterial transforming principle

an experiment proposed by Frederick Griffith in 1928 which suggested that a "transforming principle" from a heat-killed virulent Pneumococcus strain can transform a non-virulent strain into a pathogenic one.

Avery, McCarty, MacLeod (1944)

biological researchers who identified DNA as the likely transforming principle in Griffith's experiment.

Hershey and Chase (1952)

concluded that the genetic material of the bacteriophage was DNA, not protein.

Edwin Chargaff

Austrian biochemist who discovered that identical quantities of A and T, C and G were present in DNA (developed the complementary base-pairing rule for DNA).

Frederick Griffith (1928)

British bacteriologist; the first person to show that hereditary information could be transferred from one cell to another horizontally rather than vertically

genome

the complete set of genetic information carried by a species

vertical transmission

gene transmission between organisms without parental reproduction

horizontal transmission

gene transmission from parents to their offspring through reproduction (aka person-to-person)

DNA replication

the process in which DNA makes a duplicate copy of itself.

transcription

synthesis of an RNA molecule from a DNA template

mRNA (messenger RNA)

a single-stranded RNA molecule that encodes the information to make a protein

hereditary material

the information which is passed from one cellular generation to the next (encoded in DNA in humans).

Pauling and Corey (1951)

biological researchers who provided the basis for research on DNA structure (proposed an alpha helix model as a structure for nucleic acid)

Watson and Crick (1953)

the two scientists who discovered the structure and shape of DNA

nucleotide

a building block of DNA, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group.

genes

DNA segments that serve as the key functional units in hereditary transmission.

chromosomes

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

nucleoid

a dense region of DNA in a prokaryotic cell.

diploid

containing two complete sets of chromosomes, one from each parent (2n)

haploid

an organism or cell having only one complete set of chromosomes (n)

gametes

human sex cells containing one set of 23 chromosomes

homologous chromosomes

matched pairs of chromosomes in a diploid organism

Chargaff's Rule

A=T and C=G

locus

position of a gene on a chromosome

Meselson and Stahl (1958)

Bacterial cells were grown in a heavy isotope of nitrogen, 15N

All the DNA incorporated 15N

Cells were switched to media containing lighter 14N

DNA was extracted from the cells at various time intervals

central dogma

theory that states that, in cells, information only flows from DNA to RNA to proteins

translation

decoding of a mRNA message into a polypeptide chain

initiation of translation

mRNA is attached to a subunit of the ribosome, the first codon is always AUG

template strand

the strand of DNA that specifies the complementary mRNA molecule

nontemplate strand

The un-transcribed partner of the template strand of DNA used in transcription.

RNA polymerase

enzyme that links together the growing chain of RNA nucleotides during transcription using a DNA strand as a template.

polypeptide

long chain of amino acids that makes proteins

amino acids

building blocks of proteins

triplet codon

three nucleotide sequence on mRNA that codes for specific amino acid

start codon

codon that signals to ribosomes to begin translation; codes for the first amino acid in a protein (AUG)

stop codon

UAG, UAA, or UGA; the codon that ends all RNA sequences.

Charles Darwin (1809-1882)

English naturalist who postulated a theory of evolution by natural selection.

Alfred Wallace (1823-1913)

"Father of Biogeography," was the first to propose that animal species have "geographies"

natural selection

a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

descent with modification

principle that each living species has descended, with changes, from other species over time

mutation

a random error in gene replication that leads to a change

silent mutation

a mutation that changes a single nucleotide, but does not change the amino acid created.

missense mutation

a point mutation in which a codon that specifies an amino acid is mutated into a codon that specifies a different amino acid.

nonsense mutation

a mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.

frameshift mutation

a mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide

insertion

a mutation involving the addition of one or more nucleotide pairs to a gene.

deletion

a change to a chromosome in which a fragment of the chromosome is removed.

genetic drift

a change in the allele frequency of a population as a result of chance events rather than natural selection.

gene flow (migration)

movement of alleles from one population to another

nonrandom mating

mating among individuals on the basis of their phenotypic similarities or differences, rather than mating on a random basis

point mutation

gene mutation involving changes in one or a few nucleotides.

degeneracy

redundancy of the genetic code; that is, most amino acids are encoded by several codons

conditional mutation

a mutation that results in a characteristic phenotype only under certain environmental conditions.

assortative mating

the type of mating that occurs when an organism selects a mating partner that resembles itself

dissassortative mating

phenotypically different individuals mate, producing an excess of heterozygotes

genetic variance

diversity of alleles and genotypes in a population

inbreeding

breeding from closely related people or animals, especially over many generations.

analogy

similarity of function and superficial resemblance of structures that have different origins (e.g. wings of a fly, moth and bird)

homoplasy

when a trait has been gained or lost independently in separate lineages over the course of evolution

phylogenetic tree

a family tree that shows the evolutionary relationships thought to exist among groups of organisms

cladistic approach

a method for constructing a phylogenetic tree that is based on identifying the unique traits of each monophyletic group.

clades

a group of organisms believed to have evolved from a common ancestor, according to the principles of cladistics.

monophyletic group

a taxonomic grouping that includes an ancestral species and all of its descendants.

ancestral characteristics

characteristics that have arisen in organisms as a result of common evolutionary descent

derived characteristics

characteristics that appear in recent parts of a lineage but not in its older members

maximum parsimony

"Occam's Razor"a principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts.

In Griffith's experiments, what made the harmless R cells grow capsules when exposed to heat-killed S cells?

DNA

In the Hershey-Chase experiment radioactive Sulfur was used to:

Be incorporated into the phage protein coat because some amino acids contain sulfur

The experiments by Hershey and Chase helped confirm that DNA was the hereditary material on the basis of the finding that:

Radioactive phosphorus was found inside the cell

If DNA of a particular species was analyzed and it was found that it contains 27 percent of adenine (A), what would be the percentage of cytosine (C)?

23 percent

Four nucleic acid samples are analyzed to determine the percentages of the nucleotides they contain. Which of the following DNA sample(s) could be double-stranded DNA? Sample 1: A(22%), G(28%), T(22%), U(0%), C(28%); Sample 2: A(30%), G(30%), T(0%), U(20%), C(20%); Sample 3: A(18%), G(32%), T(0%), U(18%), C(32%); Sample 4: A(29%), G(29%), T(21%), U(0%), C(21%)

Sample 1

Your chromosomes are located and they are made of ____ .

inside the nucleus, DNA

A nucleotide is made of _.

sugar + phosphate + nitrogen base

A molecule of RNA (ribonucleic acid) contains the bases _.

adenine, guanine, cytosine, and uracil

Which of the following does cytosine pair with?

Guanine

Prokaryotes contain a _ chromosome, and eukaryotes contain chromosomes.

double-stranded circular; double stranded linear

How long would the peptide be that is translated from this mRNA sequence: 5'- AUGGGCUACCGA -3'?

4 amino acids

What is the correct sequence of steps in the central dogma?

DNA->RNA->Protein

Where does transcription take place in human cells?

Nucleus

Where does translation take place in eukaryotic cells?

Cytoplasm

Transcribe the following DNA sequence (non template strand): 5'-ATGGCCGGTTATTAAGCA-3'

5'-AUGGCCGGUUAUUAAGCA-3'

In which of the following pairs do both evolutionary processes introduce new genetic variation into a population?

Mutation and gene flow

Mutation can be defined as the addition of genetic variation that increases the hereditary diversity of a population.

True

If an allele has a frequency of 1:

It is found in 100% of the population

When male lions reach sexual maturity, they leave their group in search of a new pride. This can alter the allele frequencies of the population through which of the following mechanisms?

Gene flow

When closely related individuals mate with each other, or inbreed, the offspring are often not as fit as the offspring of two unrelated individuals. Why?

Inbreeding can bring together rare, deleterious mutations that lead to harmful phenotypes.

Which statement about analogies is correct?

a. They occur only as errors.

b. They are synonymous with homologous traits.

c. They are derived by similar environmental constraints.

d. They are a form of mutation.

C

What do scientists use to apply cladistics?

homologous traits

What is true about organisms that are a part of the same clade?

a. They all share the same basic characteristics.