Grade 12 Biology - Genetics

Glycosyl Bond

A bond between a sugar and another organic molecule by way of an intervening nitrogen or oxygen atom

Ribosomal RNA (rRNA)

A form of RNA that binds with ribosomal protein to form ribosomes

Single-Stranded Binding Proteins (SSBs)

A protein that keeps separated strands of DNA apart

RNA (Ribonucleic Acid) Primer

A sequence of 10 to 60 RNA bases that is annealed to a region of single-stranded DNA for the purpose of initiating DNA replication

Nitrogenous Base

An alkaline, cyclic molecule containing nitrogen

DNA Polymerase I

An enzyme that removes RNA primers and replaces them with the appropriate deoxyribonucleotides during DNA replication

Phosphodiester Bond

Bonds within any molecules that join two parts through a phosphate group

Proteins

Complex molecules composed of one or more polypeptide chains made of amino acids and folded into specific three-dimensional shapes that determine protein function

Joachim Hammerling

Determined that the hereditary information was in the nucleus in 1930

Erwin Chargaff

Discovered proportional amounts of A = T and G = C in 1949 (aka "Chargaff's Rule")

Friedrich Miescher

Distinguished between protein and another chemical he called nuclein (DNA) in 1869

RNA Polymerase

Enzyme that transcribes DNA into complementary mRNA

Phosphate Group

Group of four oxygen atoms surrounding a central phosphorous atom found in the backbone of DNA

Telomeres

Long sequences of repetitive, noncoding DNA on the end of chromosomes

Nucleotides

Molecules that consists of a five-carbon sugar (deoxyribose or ribose) with a nitrogenous base attached to their 1' carbon and a phosphate group attached to their 5' carbon

Complementary Base Pairing

Pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand; adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C)

Upstream

Region of DNA adjacent to the start of a gene

Okazaki Fragments

Short fragments of DNA that are a result of the synthesis of the lagging strand during DNA replication

Pyrimidines

Single Ringed Structures; Thymine (T) and Cytosine (C)

Start Codon

Specific codon (AUG for RNA, or TAC for DNA) that signals to the ribosome that the translation commences at that point

Deoxyribose Sugar

Sugar molecule containing five carbons that has lost the -OH (hydroxyl group) on its 2' (2 prime) carbon

DNA Gyrase

The bacterial enzyme that relieves the tension produced by the unwinding of DNA during replication

Messenger RNA (mRNA)

The end product of transcription of a gene, mRNA is translated by ribosomes into protein

DNA Polymerase III

The enzyme responsible for synthesizing complementary strands of DNA during DNA replication

Primase

The enzyme that builds RNA primers

Primary Transcript

The mRNA that has to be modified before exiting the nucleus in eukaryotic cells

Amino Acid

The monomer unit of a polypeptide chain that is composed of a carboxylic acid, an amino group, and a side group that differentiates it from other amino acids

Leading Strand

The new strand of DNA that is synthesized continuously during DNA replication

Anneal

The pairing of complementary strands of DNA through hydrogen bonding

Translation

The process by which a ribosome assembles amino acids in a specific sequence to synthesize a specific polypeptide coded by messenger RNA

Transcription

The process in which DNA is used as a template for the production of complementary messenger RNA molecules

Replication Fork

The region where the enzymes replicating a DNA are bound to untwisted, single-stranded DNA

Coding Strand

The strand of DNA that is not used for transcription and is identical in sequence to mRNA, except it contains uracil instead of thymine

Template Strand

The strand of DNA that the RNA polymerase uses as a guide to build complimentary mRNA

Alfred Hershey & Martha Chase

Used bacteriophage to prove that DNA carries the hereditary information and not the proteins in 1952

Deoxyribonucleic Acid (DNA)

A double-stranded polymer of nucleotides (each consisting of a deoxyribose sugar, a phosphate, and four nitrogenous bases) that carries the genetic information of an organism

Transfer RNA (tRNA)

A form of RNA that is responsible for delivering amino acids to the ribosomes during the process of translation

Genes

A sequence of nucleotides in DNA that performs a specific function such as coding for a particular protein

Template

A single-stranded DNA sequence that acts as the guiding pattern for producing a complementary DNA strand

Frederick Griffith

Determined that protein is not the hereditary material (the Transforming Principle) in 1920

Purines

Double Ringed Structures; Adenine (A) and Guanine (G)

Antiparallel

Parallel but running in opposite directions; the 5' end of one strand of DNA aligns with the 3' end of the other strand in a double helix

Semiconservative

Process of replication in which each DNA molecule is composed of one parent strand and one newly synthesized strand

Promoter

Sequence of DNA that binds RNA polymerase upstream of a gene (A's and T's)

Terminator Sequence

Sequence of bases at the end of a gene that signals the RNA polymerase to stop transcribing

Codon

Sequence of three bases in DNA or complementary mRNA that serves as a code for a particular amino acid

Stop Codons

Specific codons (UAA, UGA, and UAG for RNA, or ATT, ACT, and ATC for DNA) that signal the end of translation to a ribosome

DNA Ligase

The enzyme that joins DNA fragments together by catalyzing the formation of a bond between the 3' hydroxyl group and the 5' phosphate group on the sugar-phosphate backbones

DNA Helicase

The enzyme that unwinds double-helical DNA by disrupting hydrogen bonds

Lagging Strand

The new strand of DNA that is synthesized in short fragments, which are later joined together