Bio 101 Lecture 8: Molecular Basis Of Inheritance

Front 1

Bacteriophages

Back 1

Viruses that infect bacteria

Front 2

Chargaff's Rules

Back 2

~the base composition of DNA varies between species

~in all species the number and A and T are equal as are the number of G and C

Front 3

Antiparallel

Back 3

containing subunits that run in opposite directions

Front 4

Semiconservative Model of Replication

Back 4

predicts that when a double helix replicates, each daughter molecule will have one old strand and one newly made strand

Front 5

Origins of Replication

Back 5

where the two DNA strands are separated, opening up a replication "bubble"

Front 6

Replication Fork

Back 6

a Y-shaped region where DNA strands are elongating

Front 7

Helicases

Back 7

enzymes that untwist the double helix at replication forks

Front 8

Topoisomerase

Back 8

corrects "overwinding" ahead of the replication forks by breaking, swiveling, and rejoining DNA strands

Front 9

Primase

Back 9

can start an RNA chain and adds RNA nucleotides one at a time using the parental DNA as a template

Front 10

DNA Polymerase

Back 10

an enzyme that catalyzes the elongation of new DNA at the replication fork

Front 11

Leading Strand

Back 11

strand where DNA polymerase synthesizes continuously, moving toward the replication fork

Front 12

Lagging Strand

Back 12

DNA polymerase works in a direction away from the replication fork

Front 13

Okazaki Fragments

Back 13

the series of segments synthesized on the lagging strand which are later joined by DNA ligase

Front 14

What direction does DNA synthesize in?

Back 14

5' to 3', where the origin of replication is at the 3' end

Front 15

Mismatch Repair

Back 15

repair enzymes correct the errors in base pairing

Front 16

Nucleotide Excision Repair

Back 16

where a nuclease cuts out the replaces damaged stretches of DNA

Front 17

Telomeres

Back 17

special nucleotide sequences at the end of DNA molecules that postpone the erosion of genes near the ends of DNA molecules

Front 18

Telomerase

Back 18

an enzyme that catalyzes the lengthening of telomeres in germ cells

Front 19

Nucleoid

Back 19

in bacteria, the region of the cell where supercoiled DNA is found

Front 20

Chromatin

Back 20

a complex of DNA and protein that is found in the nucleus of most eukaryotic cells

Front 21

Nucleosome

Back 21

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

Front 22

Euchromatin

Back 22

loosely packed chromatin

Front 23

Heterochromatin

Back 23

highly condensed regions of chromatin; typically happens during interphase

Front 24

Gene Expression

Back 24

the process by which DNA directs protein synthesis and includes transcription and translation

Front 25

Transcription

Back 25

synthesis of a polypeptide using information in the mRNA

Front 26

Ribosomes

Back 26

the sties of translation

Front 27

Messenger RNA

Back 27

(mRNA) the product of transcription

Front 28

Central Dogma

Back 28

The concept that cells are governed by a cellular chain of command: DNA --> RNA --> Protein

Front 29

Triplet Code

Back 29

a series of nonoverlapping, three-nucleotide words

Front 30

Template Strand

Back 30

one of the two DNA strands that provides a template for ordering the sequence of complementary nucleotides in an RNA transcript

Front 31

Codons

Back 31

mRNA base triplets that are read in the 5` to 3` direction that specify one of 20 amino acids to be arranged in a polypeptide

Front 32

Reading Frame

Back 32

correct groupings that codons must be read in order for the correct polypeptide to be produced

Front 33

RNA polymerase

Back 33

catalyzes RNA synthesis by prying apart DNA strands and hooking together RNA nucleotides

Front 34

Promoter

Back 34

the DNA sequence where RNA polymerase attaches

Front 35

Terminator

Back 35

the sequence that signals the end of transcription

Front 36

Transcription Unit

Back 36

the stretch of DNA that is transcribed

Front 37

3 Stages of RNA Transcription

Back 37

~Initiation

~Elongation

~Termination

Front 38

Transcription Factors

Back 38

mediate the binding of RNA polymerase and the initiation of transcription

Front 39

Transcription Initiation Complex

Back 39

the completed assembly of transcription factors and RNA polymerase II bound to a promoter

Front 40

TATA Box

Back 40

a promoter that is crucial in forming the initiation complex in eukaryotes

Front 41

RNA Processing

Back 41

the modifying of pre-mRNA by enzymes before the genetic messages are dispatched to the cytoplasm

Front 42

Introns

Back 42

noncoding regions of RNA

Front 43

Exons

Back 43

regions of RNA that are expressed and usually translated into amino acid sequences

Front 44

RNA splicing

Back 44

removes introns and joins exons, creating mRNA molecule with a continuous coding sequence

Front 45

Spliceosomes

Back 45

a variety of proteins and several small nuclear ribonucleoproteins (snRNPs) that recognize the splice sites

Front 46

Ribozymes

Back 46

catalytic RNA molecules that function as enzymes and can splice RNA

Front 47

Alternative RNA splicing

Back 47

some genes can encode more than one kind of polypeptide depending on which segments are treated as exons during splicing

Front 48

Domains

Back 48

a modular architecture often had by proteins consisting of discrete regions

Front 49

tRNA

Back 49

transfer amino acids to the growing polypeptide chain in a ribosome

Front 50

Wobble

Back 50

flexible pairing at the third base of a codon that allows some tRNAs to bind to more than one codon

Front 51

Ribosomal RNA

Back 51

is the RNA component of the ribosome and is essential for protein synthesis

Front 52

P site

Back 52

holds the tRNA that carries the growing polypeptide chain

Front 53

A SIte

Back 53

holds the tRNA that carries the next amino acid to be added to the chain

Front 54

E site

Back 54

the exit site where discharged tRNAs leave the ribosome

Front 55

3 Stages of Translation

Back 55

~Initiation

~Elongation

~Termination

Front 56

Polyribosome

Back 56

formed after a number of ribosomes translate a single mRNA simultaneously

Front 57

Free Ribosomes

Back 57

synthesize proteins that function in the cytosol

Front 58

Bound Ribosomes

Back 58

make proteins of the endomembrane system and proteins that are secreted from the cell

Front 59

Signal Peptide

Back 59

what polypeptides destined for the ER or for secretion are marked by

Front 60

Mutations

Back 60

changes in the genetic material of a cell or virus

Front 61

Point Mutations

Back 61

chemical changes in just one base pair of a gene

Front 62

Mutagens

Back 62

physical or chemical agents that can cause mutation

Front 63

Nucleotide-Pair Substitution

Back 63

replaces one nucleotide and its partner with another pair of nucleotides

Front 64

Silent Mutations

Back 64

have no effect on the amino acid produced by a codon because of redundancy in the genetic code

Front 65

Missense Mutation

Back 65

still codes for an amino acid, but not the correct one

Front 66

Nonsense Mutations

Back 66

change an amino acid codon into a stop codon, nearly always leading to a nonfunctional protein

Front 67

Insertions and Deletions

Back 67

additions or losses of nucleotide pairs in a gene

Front 68

Frameshift Mutation

Back 68

an insertion of deletion of nucleotides that alter the reading frame