Cell Biology Genes and Chromosomes

Genes

Full DNA sequence required for synthesis of functional protein or RNA

Exons

coding regions of genes

Introns

noncoding regions of genes

Enhancer Sites

region of gene that controls transcription

Single mRNA

transcribed from operon

Beginning of each coding region

ribosomes start translation at

several

how many polypeptides are produced from a single mRNA

Polycistronic

A single mRNA molecule that contains the coding sequence for two or more different proteins

A single mutation can affect expression of several proteins

consequence of polycistronic mRNA

monocistronic

single mRNA encodes a single protein (Eukaryotic)

Alternate Poly (A) Sites

A way that multicellular organisms process mRNA to produce slightly different proteins (Same 5’ exons, different 3’)

Exon Skipping

A way that multicellular organisms process mRNA to produce slightly different proteins (same 5’ and 3’, different internal exon)

Solitary

When genes are singly represented in the genome

Duplicated

when genes exist as repeats in the genome

Gene Family

type of repeated gene, encode proteins with similar not identical AAs sequence

Kinases and Immunoglobulins

example of gene family

Tandemly Repeated Sequences

type of repeated gene, genes that encode rRNAs, tRNAs, and histones, encodes identical proteins

Repetitious DNA

Type of repeated gene, 2 main types, simple sequence DNA and mobile DNA or moderately repeated.

1-500 bp sequences

simple sequence DNA consists of different set of repeats of

Satellite DNA

Simple sequence DNA repeats that stretch to 100 kb long

Minisatellites

Simple sequence DNA repeats that stretch to 1-5 kb long

Near centromere

most simple sequence DNA is located

particular chromosome

Some simple sequence DNA is specific to a

Basis for DNA fingerprinting technology

the number of repeats for some simple sequence DNA being unique to each individual is the

Simple Sequence DNA

the function of this DNA is unknown

Transposition

when mobile DNA segments can be inserted into new sites in the genome

DNA (Transposon)

Mobile DNA may transpose as

RNA Intermediate

Mobile DNA may also transpose as

Reverse Transcriptase

converts RNA to DNA

Viral

Type of retrotransposon that encodes reverse transcriptase and integrase

Nonviral

type of retrotransposon that’s most common, lines and sines

Lines (L1 Family))

Type of nonverbal retrotransposon, codes for DNA binding proteins and reverse transcriptase.

SINES

Type of nonverbal retrotransposon, Alu sequences, do not code for any protein.

Mobile DNA

Has no known function

Inherited Recessive Diseases

LINE and SINE sequences inserted into exons linked to

Hemophilia

LINE causes

Neurofibroma

SINE causes

Proteins

DNA exists in a highly compact conformation associated with equal mass of … (Chromatin)

Histones

most abundant proteins are … (family of proteins in all eukaryotes)

H1, H2A, H2B, H3, and H4

5 major types of histones

Extended

Form of chromatin, resembles beads on a string, (Bead, nucleosome)

2

Extended chromatin consists of 147bp of DNA wrapped around … copies of H2A, H2b, H3, and H4

Linker DNA

Extended chromatin is connected by

Actively being transcribed

Chromatin that is … assumes extended conformation

Condensed

Form of chromatin, consisted of nucleosomes packing into a spiral conformation.

Solenoid Structure

In condensed chromatin, H1 is bound outside of each nucleosome and it thought to help stabilize the

Scaffold-associated regions (SARs)

In condensed chromatin, 30 nm fiber is looped and attached to protein scaffold at … to produce metaphase

not being transcribed

Chromatin … exists in condensed conformation

Origin

site of initiation of DNA replication, yeast autonomously replicating sequences. Required for replication and stable inheritance of chromosomes.

Centromere

needed for separation of sister chromatids during mitosis. Required for replication and stable inheritance of chromosomes.

Telomere

multiple, tandem repeats of short sequence at end of eukaryotic chromosome.

Telomerase

Telomeres are produced by modified reverse transcriptase called

RNA template that is part of the enzyme

Telomerase adds nucleotides to the 3’ hydroxyl end of lagging strand template directed by a

Telemerase

prevents progressive shortening of lagging strand