College Bio Molecular Genetics Ch 16, 17, 18

Edwin Chargoff

Known for discovering the chemical components of genetics

Rosalind Franklin

Provided the X-ray critical to the finding of DNA structure

James Watson and Francis Crick

Credited with figuring the structure of DNA “Twisted Ladder”

Double Helix, sides made of sugar phosphate, nitrogenous bases as steps, antiparallel, A=T C=G

Antiparallel

Sides of model run in opposite direction

Replication

The making of DNA from an existing DNA strand, Synthesis, Semiconservative: product i=consist of old strand and newly synthesized strand

DNA polymerase

A group of enzymes that catalyzes the elongation of new DNA, adds nucleotides to the growing chain

Leading Strand

5’ to 3’ strand, replication occurs continuously

Lagging Strand

3’ to 5’ strand, copied in series of segments

Okazaki Fragments

Separate pieces lagging strand is synthesized

DNA Ligase

Used to seal together Okazaki fragments

Mutation

Occurs if something goes wrong during replication

Nucleosome

The first level of packaging in chromosomes involves DNA wrapped around proteins called histones, resembles beads on a string.

30nm fiber

The strings of nucleosomes folded

Looped domains

Further folding of the 30nm fiber

Metaphase chromosome

Looped domains fold into

Gene Expression

The process by which the DNA directs the synthesis of proteins

Transcription

The synthesis of RNA using DNA as a template, takes place in the nucleus

mRNA

Carries the genetic message, produced during transcription

Translation

Production of polypeptide chain using the mRNA transcript, occurs at the ribosome

Template Strand

One strand of DNA is transcribed, or read

RNA Polymerase

Any message that separates the two DNA strands

Promoter

The start or sequence at which RNA polymerase attaches to

Terminator

Sequence that signals the end

Transcription Unit

The entire stretch of DNA that is transcribed

Initiation

The start of transcription or translation

Elongation

The adding or reading of transcription or translation

Termination

The stopping or ending of transcription or translation

5’ cap

Post transcription modification added to start/top of sequence

Poly-A tail

Post transcription added to end of sequence

Introns

Non coding, spliced/cut out sections of the new RNA strand

Exons

Coding, section that splice/come together and stay

rRNA

Ribosomal RNA

tRNA

Transfer amino acids from cells cytoplasm to ribosome

Mutagens

Substances or forces that interact with DNA in ways that cause mutations

Oberon

Genes clustered into units are called this

Operator

Controls the access of RNA polymerase to the genes

Regulatory genes

Produce repressor proteins that may bind to the operator site

Repressive operon

Normally on but can be inhibitied

Inducible operon

Is normally off but can be activated

DNA Methylation

Causes DNA to be more tightly packed, reducing gene expression, closed book

Histone Acetylation

Makes chromatin less tightly packed and encourages transcription, open book

Cell division

Mitosis, increases the number of cells

Cell differentiation

The process by which cells become specialized in structure and function

Oncogenes

Cancer-causing genes

Porto-oncogenes

Genes that code for proteins that are responsible for normal cell growth

P53 gene

Tumor suppressor gene

Apoptosis

Suicide genes whose products cause cell death