BSC2010 - Chapter 11 Vocabulary

DNA

deoxyribonucleic acid, a self-replicating material present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information.

replication

Copying process by which a cell duplicates its DNA

chromosomes

threadlike structures made of DNA molecules that contain the genes

Frederick Griffith

Discovered transformation during an experiment that involved injecting mice with smooth S cells, rough R cells, heat-killed S cells, and heat-killed S cells with living R cells.

transformation

process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria

Avery, MacLeod, McCarty

Determined that DNA was Griffith's "Transforming Factor."

DNAse

digests DNA

RNAse

degrades RNA

protease

enzyme that digests protein

nucleic acids

DNA and RNA

nucleotides

Basic units of DNA molecule, composed of a sugar, a phosphate, and one of 4 DNA bases

double helix

two strands of nucleotides wound about each other; structure of DNA

genome

all of an organism's genetic material

purines

Bases with a double-ring structure.

Adenine and Guanine

pyrimidines

cytosine, thymine, uracil

phosphoester linkage

Bond that holds together two nucleotides

DNA backbone

Made of deoxyribose SUGAR and Phosphate

DNA directionality

one end has an exposed hydroxyl group on the 3' carbon of deoxyribose and the other end has an exposed phosphate group on a 5' carbon

Erwin Chargaff

Discovered that DNA composition varies, but the amount of adenine is always the same as thymine and the amount of cytosine is always the same as guanine.

Rosalind Franklin

Woman who generated x-ray images of DNA, she provided Watson and Crick with key data about DNA

Watson and Crick

discovered the structure of DNA

base pairs

A-T

G-C

AT/GC rule

Refers to the phenomenon that an A in one DNA strand always hydrogen-bonds with a T in the opposite strand, and a G in one strand always bonds with a C.

complementary DNA strands

The relation between the two nucleotide strands of DNA in which each purine on one strand pairs with a specific pyrimidine on the opposite strand (A pairs with T, and G pairs with C).

antiparallel strands

Strands parallel to each other going in opposite directions (3'-5' and 5'-3')

major groove

a groove that spirals around the DNA double helix; provides a location where a protein can bind to a particular sequence of bases and affect the expression of a gene

minor groove

the smaller of the two grooves in the DNA double helix

DNA replication

the process of making a copy of DNA

semiconservative replication

Method of DNA replication in which parental strands separate, act as templates, and produce molecules of DNA with one parental DNA strand and one new DNA strand

Messelson and Stahl

Used light and heavy nitrogen to prove the theory of semiconservative replication

origin of replication (ori)

A sequence of DNA at which replication of DNA is initiated.

replication forks

portions of DNA where the double helix separates during DNA replication

bidirectional replication

the process in which DNA replication proceeds outward from the origin in opposite directions

DNA Helicase

An enzyme that unwinds the DNA double helix during DNA replication

DNA Topoisomerase

Relives additional coiling ahead of replication fork

single strand binding proteins

bind to and stabilize single-stranded DNA

DNA Polymerase

Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule

Deoxynucleoside triphosphates

Free nucleotides with three phosphate groups; Breaking covalent bond to release pyrophosphate (two phosphates) provides energy to connect nucleotides

DNA primase

synthesizes a short RNA primer to provide a 3'-OH group for the attachment of DNA nucleotides

leading strand

The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction.

lagging strand

A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' to 3' direction away from the replication fork.

Okazaki fragments

Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.

DNA Ligase

an enzyme that eventually joins the sugar-phosphate backbones of the Okazaki fragments

Proofreading

function of DNA polymerase in which it reads the newly added base before adding the next one

telomere

repetitive DNA at the end of a eukaryotic chromosome

telomerase

An enzyme that catalyzes the lengthening of telomeres. The enzyme includes a molecule of RNA that serves as a template for new telomere segments.

chromatin

Substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones

histones

Globular protein that assist in DNA packaging in eukaryotes. Histones form octamers around which DNA is wound to form a nucleosome.

nucleosome

Bead-like structure in eukaryotic chromatin, composed of a short length of DNA wrapped around a core of histone proteins

30-nm fiber

nucleosome units organized into a more compact structure that is 30 nm in diameter

nuclear matrix

a framework of protein fibers extending throughout the nuclear interior

nuclear lamina

A netlike array of protein filaments lining the inner surface of the nuclear envelope; it helps maintain the shape of the nucleus.

radial loop domains

A loop of chromatin, often 25,000 to 200,000 base pairs in size, that is anchored to the nuclear matrix.

heterochromatin

Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed.

euchromatin

The less condensed form of eukaryotic chromatin that is available for transcription.