Nucleic Acids - IB Biology HL

diffraction

a beam of X rays is directed at a material, most of ti passes through but some is scattered by the particles

supernatant

the (usually) clear liquid left behind after a precipitate has been spun down to the bottom of a vessel by centrifugation

centrifugation

process of separating out particles of different sizes and densities by spinning them at high speed in a centrifuge.

angstrom

10^-10m

purine

Adenine and Guanine

pyrimidines

Thymine and Cytosine

nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base; it is what DNA is composed of

histone

protein that organizes chromosomes and around which DNA wraps

nucleosome

a structural unit of a eukaryotic chromosome, consisting of a length of DNA coiled around a core of 8 histones.

H1 histone

the only histone that is not in the nucleosome core (DNA is not wrapped around it. Ties the beads together in a string; bind DNA to core particle.

polymerase chain reaction (PCR)

a method of producing thousands of copies of DNA segment using the enzyme DNA polymerase

polymerase

an enzyme that brings about the formation of a particular polymer, especially DNA or RNA; responsible for covalently linking the deoxyribonucleotide monophosphate to the 3' end of the growing strand.

helicase

an enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands.

leading strand

the new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction; starts with a RNA primer

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.

DNA gyrase (topoisomerase)

djusts supercoil density by relaxing supercoil tension around DNA's

helical axis thereby relieving structural stress generated by the unwinding of the DNA helix during replication

DNA polymerase I

a DNA enzyme that removes RNA primers and replaces them with DNA

DNA polymerase III

a DNA enzyme that adds nucleotides to the 3' end of the elongating DNA strand.

DNA ligase

an enzyme that connects two fragments of DNA to make a single fragment

DNA primase

an enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.

Okazaki fragments

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

single strand binding proteins

proteins that bind to the unpaired DNA strands, keeping them from re-pairing

phosphodiester bond

when DNA polymerase III cleaves the two additional phosphates and uses energy released to form this bond with the 3' end of a nucleotide chain; type of covalent bond in DNA and RNA which involves two hydroxyl groups and one phosphate group

telomeres

repetitive base sequences at the ends of chromosomes; ensures that only non-coding genes are lost and not valuable genes.

Satellite DNA

highly repetitive sequences of DNA, commonly used for DNA profiling

Introns

non-coding sequences within genes, are removed from mRNA before it is translated.

Regulating gene expression

are sites where proteins can bind that either promote or repress the transcription of an adjacent gene

Genes for tRna and rRNA

transcription of these genes produces the transfer RNA used during translation and also the ribosomal RNA that forms much of the structure of the ribosome.

variable number tandem repeats (VNTR)

a short nucleotide sequence that shows variations between individuals in terms of the # of times the sequence is repeated

gel electrophoresis

procedure used to separate and analyze DNA fragments by placing a mixture of DNA fragments at one end of a porous gel and applying an electrical voltage to the gel

Sanger process

a method used in DNA sequencing

transcription

(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA

terminator

a sequence of nucleotides in DNA that marks the end of a gene and signals RNA polymerase to release the newly made RNA molecule and detach from the DNA.

chromosome

a threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins.

species

a group of organisms which are structurally similar and able to pass their genetic traits onto their offspring

linker DNA

short section or strand of DNA which occurs between adjacent nucleosomes; connects nucleosomes

X-ray diffraction

process used by Rosalind Franklin to make images of DNA that helped reveal the structure of DNA; bending of X-rays as it passes through a substance

base pairing

process in DNA replication and protein synthesis in which nitrogenous base pairing is very specific

semi conservative

type of replication in DNA in which each new DNA molecule has one original strand of the parent molecule

virus

infectious particle composed of protein and nucleic acid not able to replicate itself outside a cell

radiation

particles given off by a substance which allow its tracking

radioactive

element or isotope which gives off energetic particles

bacterial cultures

laboratory collection or association of bacteria maintained for study

bacteriophage

a type of virus which infects bacteria

primer

An already existing RNA chain bound to template DNA to which DNA nucleotides are added during DNA synthesis.

synthesis

constructing complex molecules from smaller, simpler ones

tRNA

transfer RNA, the molecule that carries an amino acid to the ribosome in protein production

centromere

region where sister chromatids attach

short tandem repeats

repeating sequence of 1-5 nucleotides which varies in number of repeats for different individuals

DNA profiling

methodofstudying DNA using restriction enzymes and gel electrophoresis

locus

the specific place where a gene is found on a chromosome

dideoxyribonucleic acid

component in nucleotides used to stop DNA replication at specific locations

base sequencing

processin which the exact sequence in a DNA fragment or molecule is produced

fluorescent marker

used to allow identification in DNA studies

mRNA

messenger RNA carries the DNA code from the nucleus to the cytoplasmic ribosomes for specific production of proteins

complementary base pairing

nitrogenous bases which pair together in nucleic acids, A-T, A-U, C-G

antisense strand

the template strand, where complementary base pairing occurs to produce mRNA

sense strand

DNA strand not transcribed in the production of mRNA, contains the same code as the mRNA which is produced on the template strand

promoter region

non-coding DNA region which binds with RNA polymerase to begin the transcription process

terminator sequence

sequence of DNA which stops the transcription process for a particular protein

RNA polymerase

an enzyme involved in the transcription process

methylation patterns

refers to the methyl groups which occur on DNA of organisms

introns

non-coding regions of DNA which are transcribed onto the mRNA molecules, they are removed before leaving the nucleus

pre-mRNA strand

original, unprocessed strand of mRNA produced in transcription

small nuclear RNAs

snRNAs also known as spliceosomes; involved in the cutting of pre-mRNA strands to remove introns

splicing

the removal of introns from mRNA

exons

sections of mRNA containing the protein coding nucleotide sequences

cap

protective structure added to the 5' end of mRNA after processing before the mRNA leaves the nucleus

poly-A tail

protective structure added to the 3' end of mRNA after processing before the mRNA leaves the nucleus

mature mRNA

final product of mRNA processing which occurs in the nucleus and will be translated at the ribosome

transcription activators

proteins which cause looping of DNA and increase expression of a gene

repressor proteins

bind to segments of DNA and prevent transcription and gene expression

silencer

segment of DNA to which a repressor protein binds

enhancer

a DNA sequence that recognizes certain transcription factors that can stimulate transcription of nearby genes.

genotype

genes of an organism for a particular trait

phenotype

visible result of an organism's genotype

translation

process of protein production which occurs at the ribosome in cells, DNA language is changed into the language of proteins

ribosome

organelle within cells where polypeptides are formed

ribosome-mRNA complex

combination of ribosome and mRNA which must occur for translation to begin

methionine

particular type of amino acid which begins the production of a polypeptide in translation

anti-codon

group of three nucleotides on tRNA which base- pair with the codon of mRNA

polysomes

group of ribosomes attached to a single strand of mRNA all producing the same polypeptide

tRNA binding sites

the A, P, and E sites on the small subunit of ribosomes that connects with the amino acid carrying tRNA molecules

polypeptide chain

large sequence of amino acids chemically combined by covalent bonds called peptide bonds

codon

a group of three bases that together code for a single amino acid

polypeptide

A polymer (chain) of many amino acids linked together by peptide bonds.

peptide bonds

covalent bond which occurs between the amino group of one amino acid and the carboxyl group of another

substrate

substance which begins a chemical reaction or process

phosphorylation

process of adding a phosphate group to a molecule, usually includes the addition of energy as well

disassembly

breaking something down into the parts of which it is made

endoplasmic reticulum

organelle involved in transport within the cell

free ribosomes

ribosomes in the cytoplasm of the cell which are not connected to the endoplasmic reticulum

signal sequence

group of amino acids coded by mRNA which controls whether a ribosome is attached to the endoplasmic reticulum or not

secretion

release of a substance from a cell, tissue, or gland

lysosome

eukaryotic cell organelle involved in hydrolytic or breakdown processes within the cell

bound ribosomes

ribosomes which are connected to the endoplasmic reticulum

R-group

the portion of each of the 20 amino acids that is different from one another

primary structure

sequence of amino acids forming the polypeptide chain of a protein

carboxyl group

-COOH