BIO 304 Exam 1 University of Kentucky

antiparalell

Opposite 5' and 3' orientations of two complimentary nucleic acid strains

base pairing

the process of two nitrogen-containing bases, or nucleotides, bonding together to form a base pair.

Complementarity

property shared between two DNA or RNA sequences

DNA Backbone

the portion of the DNA double helix that provides structural support to the molecule.

deoxynucleotide triphosphate (dNTP)

Triphosphate forms of deoxynucleotides.

hydrogen bond

Weak electrostatic attraction formed by the sharing of a positively charged hydrogen atom by negatively charged oxygen and nitrogen atoms. Hydrogen bonds form between complementary nucleotides to hold nucleic acid strands together.

origin of replication

The specific sequence at which DNA replication begins.

PCR

A laboratory method for controlled replication of a specific target sequence of DNA in successive cycles. Using two short single-stranded primers that bind to sequences on opposite sides of the target sequence, exponential replication of the target sequence occurs.

Phosphodiester bond

A type of covalent bond formed between two nucleotides in a nucleic acid strain. Formed between the 5′ phosphate group of one nucleotide and the 3′ OH of the adjacent nucleotide

Primer

a short, single-stranded nucleic acid sequence that acts as a starting point for DNA synthesis

Replication fork

In DNA replication, the site of the replisome structure, and the site of synthesis of leading strand and lagging strand DNA.

Semiconservative replication

The established method of DNA replication in which each strand of a parental duplex acts as a template for daughter strand synthesis and each daughter duplex is composed of one parental strand and a complementary daughter strand

Supercoiling

The superhelical twisting of covalently closed circular DNA

Helicase

In DNA replication, the enzyme responsible for breaking hydrogen bonds between complementary nucleotides of a DNA duplex. Unwinding of the strands occurs ahead of the advancing replication fork.

Topoisomerase

Enzyme that relaxes DNA supercoiling by controlled strand nicking and rejoining

DNA polymerase

The large multisubunit complex responsible for the synthesis of new strands of DNA during DNA replication or DNA repair.

DNA Ligase

An enzyme active in DNA repli-cation that joins together segments of a DNA strand by catalyzing formation of a phosphodi-ester bond.

Taq polymerase

A DNA synthesis enzyme that can withstand the high temperatures of PCR

Transcription

The cellular process that synthe-sizes RNA strands from a DNA template strand.

mRNA

A form of RNA transcribed from a gene and subsequently translated to produce a polypeptide or protein.

Untranslated Region (UTR)

The region of mRNA before the start codon AUG, it allows the ribosome to bind to mRNA

Coding Sequence (CSD)

Portion of a gene's DNA or RNA

RNA polymerase

The enzyme that catalyzes the synthesis of RNA

Sigma Subunit

Accessory protein that changes the promoter-recognition specificity of the bacterial RNA polymerase core.

Pribnow box

A specific consensus sequence component of the bacterial promoter with a location centered at approximately -10 relative to the start of transcription.

-35 Box

A specific consensus sequence of the bacterial promoter at which RNA polymerase is bound

Promoter

A specific consensus sequence of the bacterial promoter at which RNA polymerase is bound

intrinsic termination

In bacterial transcription, the DNA sequence-dependent mechanism for transcription termination. Inverted repeat DNA sequences induce formation of 3′ mRNA stem loop (hairpin) structures that are followed by multiple uracils (transcribed from adenines).

rho-dependent termination

The process of bacterial transcription termination involving rho protein.

hairpin/stem loop

Short double-stranded segments of RNA topped by a single-stranded loop containing unpaired nucleotides. Also known as a hairpin structure

translation

The process taking place at ribosomes to synthesize polypeptides. Complementary base pairing between mRNA codons and tRNA anticodons determines the order of amino acids composing the polypeptide.

rRNA

A group of RNA molecules that compose part of the structure of ribosomes.

tRNA

A family of small RNA molecules that each bind a specific amino acid and convey it to the ribosome, where the antico-don sequence undertakes complementary base pairing with an mRNA codon during translation.

Large ribosome subunit

The larger of the two subunits of the ribosome. Catalyzes peptide bond formation

small ribosome subunit

Smaller of the two subunits of the ribosome, decodes genetic information

A site

The site on a ribosome at which incoming charged tRNAs match their anticodon sequence with mRNA codons.

P site

The site on the ribosome where amino acids are joined by a peptide bond.

E site

On the ribosome, the site through which an uncharged tRNA exits.

Shine-Dalgarno sequence

In bacterial translation, the 5′ UTR mRNA consensus sequence that pairs with nucleotides near the 3′ end of 16S rRNA in the small ribosomal subunit to orient the start codon on the ribosome

fMet

the amino acid coded by the AUG codon, which is the start codon for protein synthesis.

Kozak sequence

A specific consensus sequence of eukaryotic mRNA that contains the authentic start codon (AUG) sequence.

Codon

The nucleotide triplet of mRNA that encodes a single amino acid.

Redundancy (of the genetic code)

multiple different codon sequences (combinations of nucleotides) can code for the same amino acid

wobble

a theory that explains how a single amino acid can be coded for by multiple codons. It was proposed by Francis Crick in 1966.

frameshift

The insertion or deletion of DNA base pairs resulting in translation of mRNA in an incorrect reading frame.

reading frame

The partitioning of sequential sets of mRNA trinucleotide segments (codons) that are used in translation to determine amino acid order of a polypeptide

anaphase

The phase of mitosis during which sister chromatids separate (anaphase A) and move to opposite poles (anaphase B).

Barr Body

The darkly staining inactive X chromosome visible in mammalian female nuclei. The result of random X inactivation.

centromere

A cytoplasmic region, containing a pair of centrioles in many eukaryotic species, from which the growth of microtubules forms the spindle apparatus during cell division.

chiasmata

Points of contact between homologous chromosomes that are coincident with crossover locations between the homologs.

chromatid

two identical halves of a replicated chromosome

chromosome

A structure composed of DNA and associated proteins that in total contain the genome of an organism

crossing over

The breakage and reunion of homologous chromosomes that results in reciprocal recombination.

cytokinesis

Part of telophase, the process of cytoplasmic division between daughter cells.

diploid (2n)

The characteristic number of chromosomes (2n) in somatic cell nuclei during the diploid phase of the eukaryotic life cycle. Equal to twice the haploid (n) number of chromosomes found in the nuclei of gametes of sexually reproducing diploid species

G1 Phase

The "Gap 1" phase of the cell cycle during which genes are actively transcribed and translated and cells carry out their normal functions.

G2 Phase

The "Gap 2" phase of the cell cycle during which the cell prepares to divide.

germline cell

The reproductive cells produced by male and female reproductive structures; sperm or pollen in male animals and plants and eggs in females.

haploid (n)

Possessing a single set of chromosomes (n); a cell or organism that possesses one-half the number of chromosomes found in diploid cells of the organism.

hemizygous

Referring to the genotype of males that carry a single copy of each X-linked gene.

heterogametic

denoting the sex which has sex chromosomes that differ in morphology, resulting in two different kinds of gamete

homogametic

denoting the sex which has sex chromosomes that differ in morphology, resulting in two different kinds of gamete,

homologous chromosomes

Chromosomes that synapse (pair) during meiosis. Chromosomes with the same genes in the same order. Also known as homologs.

kinetochore

The site of attachment of multiple proteins that connects a spindle fiber microtubule to the centromeric region of a chromosome. Forms during M phase of cell division.

M phase

The cell division phase of the cell cycle. Follows interphase.

meiosis

The process of cell division occurring in germ-line cells. Produces four haploid gam-etes or spores through two successive nuclear divisions in diploid species.

meiosis I

First nuclear division characterized by homologous chromosomes separating.

Meiosis II

Second nuclear division characterized by sister chromatids separating.

metaphase

mitosis

The stage of M phase during which chromosomes align in the middle of the cell.

nonsister chromatids

A chromatid belonging to a homologous chromosome. Nonsister chromatids of homologs are involved in crossing over

nondisjunction

The failure of homolog or sister chromatid separation during cell division. Results in nuclei with the wrong number of chromosomes

prophase

The stage of M phase during which chromosome condensation occurs

pseudoautosomal region

Homologous regions on the X and Y chromosomes that syn-apse and cross over

reduction division

a type of cell division that reduces the number of chromosomes in a cell by half

S phase

The middle phase of interphase, during which DNA replication takes place.

sex-linked inheritance

The inheritance of genes on the sex chromosomes.

sister chromatids

The identical DNA duplexes that are produced by DNA replication and are temporarily joined to one another during the early stages of cell division.

somatic cell

any cell of a living organism other than the reproductive cells.

spindle fiber microtubules

long protein strands that make up the spindle, which is a structure that moves chromosomes during cell division.

synapsis

The close approach and contact between homologous chromosomes during early prophase I in meiosis.

synaptonemal complex

A specialized three-layer protein complex, consisting of a central element and two lateral elements, that forms between homologous chromosomes at synapsis

telophase

The last stage of M phase, in which the nuclear contents are divided (karyokinesis) and the daughter cells are divided (cytokinesis).

X-linked dominant

X-linked inheritance

The pattern of inheritance characteristic of genes located on the X chromosome.

X-linked recessive

A pattern of inheritance consistent with the transmission of a recessive allele of a gene on the X chromosome

Y-linked inheritance

The exclusively male-to-male transmission of genes on the Y chromosome

Z/W system

The sex chromosome inheritance system in species in which the male is homo-gametic (ZZ) and the female is heterogametic (ZW)

Autosomal dominant inheritance

A pattern of hereditary transmission in which the dominant allele of an autosomal gene results in the appearance of the dominant phenotype

Autosomal recessive inheritance

A pattern of hereditary transmission in which the recessive allele of an autosomal gene results in the appearance of the recessive phenotype.

bionomial probability

A probability function using two coefficients, a and b, whose sum equals 1 and whose products predict the prob-ability of events

blending theory of heredity

An obsolete theory of heredity proposing that the traits of offspring are the average of parental traits

chi-square test

A statistical test to compare the observed results of an experiment with the results predicted by chance.

conditional probability

A probability prediction that is dependent on another previous event having taken place.

controlled genetic cross

Genetic crosses con-trolled by an investigator who usually knows the genotypes and/or phenotypes of the organisms being crossed

degrees of freedom (df)

The number of independent variables in an experiment. In a chi-square test, most often the number of outcome class minus 1 (n - 1).

dichotomous phenotype

a discreet trait that has two contrasting phenotypic possibilities

F1 (first filial) generation

The first generation of offspring. In genetic experiments, usually the offspring produced by crossing pure-breeding parents.

F2 (second filial) generation

The second generation, produced by crossing F1 organisms

forked-line diagram

A method for diagramming the probabilities of outcomes in a branching format