Biology Exam 3

Front 1

Linkage

Back 1

When 2 or more genes are on the same chromosome.

They tend to stay together during formation of gametes

Front 2

Independent Assortment of Genes

Back 2

Occurs due to them being on different chromosomes

Front 3

Relationship between:
Recombination Frequency & True Genetic Distance

Back 3

As genetic distance increases, the recombination frequency first increases in a linear fashion , but then levels off to a frequency of 0.5

Front 4

Map Distance

Back 4

A genetic map contains the distances between the gene loci measured in terms of the frequency of recombination. Termed in map units.
1 m.u. = 1% recombination.

(Number of recombinants observed / total offspring) x 100

Front 5

Crossing Over

Back 5

if the distance between genes is great, genetic exchange between two arms of a chromosome pair is more likely to occur

Front 6

Drosophila sex

Back 6

influenced by the number of copies of X chromosome

Front 7

Autosomes

Back 7

of the 23 pairs of human chromosomes, 22 pairs are similar in the location of genes and are found in both males and females.

Front 8

Nondisjunction

Back 8

chromosomes fail to separate during meiosis, leading to an abnormal diploid number

Front 9

Monosomics

Back 9

humans who have lost at least one copy of an autosome

Hint 9

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Front 10

Trisomy

Back 10

most common when chromosome 21 has 3 copies instead of 2

Front 11

Genetic Disorder

Back 11

Condition of alternative alleles with detrimental effects existing in significant proportions in populations.

Front 12

Cystic Fibrosis

Back 12

Most common fatal genetic disorder of Caucasians.

Front 13

Sickle Cell Anemia

Back 13

Defective hemoglobin differs from the normal hemoglobin by a single amino acid substitution.

Front 14

Hemophilia

Back 14

X-linked (sex linked) recessive condition

Front 15

Huntington's Disease

Back 15

Hereditary disease that is caused by a dominant allele but does not express phenotypically until affected individuals are in middle age.

Front 16

Aminocentesis

Back 16

Used to diagnose genetic disorders in fetuses

Front 17

Offspring Gender Control

Back 17

Offspring gender is determined by the XY male rather than the XX female because maleness is the result of the presence of the Y chromosome which contains the SRY gene.

Front 18

Testcross

Back 18

Can determine whether an individual that displays a dominant phenotype is either heterozygous or homozygous for the trait thereby generating genotype information from phenotype information

Front 19

SRY Gene

Back 19

Codes for androgen testosterone; without release of testosterone and correct reception of hormone during development, an XY individual would be born with an XX external phenotype

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XO Individual

Back 20

Lack of a Y chromosome would result in a female

Front 21

XXY Individual

Back 21

Presence of Y chromosome results in a male.

Front 22

Polymorphisms

Back 22

Genetic differences in members of a population

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Mitochondrial DNA

Back 23

Inherited by both male and female offspring but comes only from the mother; so while it can be used to determine the relationship within a maternal line, it does not identify specific individuals.

Front 24

Telomere

Back 24

Telomerase enzymes ensure that the ends of the lagging strands are replicated correctly.

Front 25

Hereditary Traits

Back 25

Results from info encoded in genes being deciphered into protiens

Front 26

Chromatin

Back 26

Complex of eukaryotic chromosomes composed of 60% protien and 40% DNA

Front 27

DNA

Back 27

Two antiparallel strands of nucleotide chains held together by hydrogen bonds between the nitrogen bases

Front 28

Nucleic Acids

Back 28

Made up of nitrogen bases, sugar, and phosphate

Front 29

Nitrogenous Bases

Back 29

Cytosine, Thymine (DNA), or Uracil (RNA):
Single ring pyrimidines

Guanine, Adenine:
Double ring pyrimidines

Front 30

Phosphodiester Bond

Back 30

Chemical bond connecting one nucleotide with the next one along the nucleic acid chain

(phosphate group of one with hydroxyl group of another)

Front 31

Hydrogen Bonds

Back 31

Hold together two antiparallel strands of nucleotide chains (DNA) by stabilizing complimentary nitrogen bases;

Adenine - Thymine: 2 H+ bonds
Guanine - Cytosine: 3 H+ bonds

Front 32

Phosphate Release

Back 32

Supplies energy for making DNA molecule

Front 33

Endergonic

Back 33

Synthesis of DNA

Front 34

Semiconservative Method

Back 34

Each original strand is used as a template to build a new strand in DNA replication

Front 35

DNA Polymerase III

Back 35

Enzyme that catalyzes the synthesis of new DNA molecule

Front 36

DNA Polymerase I

Back 36

Erases the primer and fills the gaps.

Front 37

DNA Primase

Back 37

Creates a short RNA Primer (required by DNA polymerase III) complementary to the DNA Template.

Front 38

DNA Helicase

Back 38

Use hydrolysis of ATP to increase efficiency of unwinding the double helix of DNA in front of polymerase.

Front 39

Initiation

Back 39

The step in DNA replication in which the replication proteins open up the double helix and prepare for complementary base pairing.

Front 40

DNA gyrase

Back 40

Relieves torque (torsion strain of the two strands)

Front 41

DNA Ligase

Back 41

Continuously required during DNA replication to join together fragments of lagging strand; DNA repair

Front 42

Elongation

Back 42

The step in DNA replication in which the proteins connect the correct sequence of nucleotides into a continuous new strand.

Front 43

Chargaff's Rules

Back 43

A pairs with T
G pairs with C
so
A% = T%
G% = C%
A% + T% + G% + C% = 100%

Front 44

Pyrophosphate

Back 44

By product of DNA Synthesis

Front 45

RNA Primer

Back 45

Required for DNA polymerase to begin DNA replication

Front 46

Discontinuous Synthesis

Back 46

Lagging strand's replication with segments of Okazaki Fragments

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3' End

Back 47

New bases are always added to this end during replication

Front 48

5' to 3' Direction

Back 48

New DNA strand (leading) is synthesized in this way

Front 49

Alternating sugars and phosphates

Back 49

Side supports of double-stranded DNA

Front 50

DNA Replication

Back 50

Two strand separated; each strand is used as a template for making duplex; synthesis on each strand is in the opposite direction; each nucleus contains one strand of the original DNA and one strand of the newly synthesized DNA

Front 51

5

Back 51

Number of nitrogen bases for use in DNA and RNA

Front 52

DNA Coding for Proteins

Back 52

Sequence of amino acids, which make up proteins, was determined by the nucleotides in a gene sequence

Front 53

Primosome

Back 53

Primase, helicase, & accessory proteins

Front 54

Replisome

Back 54

Large macromolecular assembly consisting of primosome & complex of 2 DNA polymerase III enzymes

Front 55

Replication Fork

Back 55

Site of the opening of the DNA strands where active replication occurs

Front 56

Time Constraints of Eukaryotic DNA Replication is Avoided By:

Back 56

Multiple origins of replication from each chromosome, which results in multiple replicons.

Front 57

Termination

Back 57

The step in DNA replication in which two replication forks moving in opposite directions may meet

Front 58

Synthesis of Lagging Strand

Back 58

Primase adds RNA primer ahead of 5' end, DNA polymerase III adds nucleotides to primer until gap is filled in. DNA polymerase I replaces primer with DNA nucleotides, and ligase seals the gap.

Front 59

Watson & Crick

Back 59

Proposed double helix model of DNA

Front 60

Heredity

Back 60

Cell's ability to use DNA information to produce specific proteins

Front 61

Gene Expression: "Central Dogma"

Back 61

Transcription & Translation =
DNA ---> RNA ---> Polypeptides/Protiens

Front 62

Structural Gene

Back 62

An organized unit of DNA sequences that enables it's information to be transcribed into RNA and ultimately results in the formation of a functional product (polypeptide --> protein)

Front 63

Ribosome

Back 63

Large rRNA/protein aggregate residing in cytoplasm

ultimately - rRNA determines form of ribosomes

Front 64

Gene Expression

Back 64

process by which information from a gene is used in the synthesis of a functional gene produce. Transcription and Translation

Front 65

Transcription

Back 65

RNA Polymerase, binding to a promoter, makes a single stranded mRNA molecule with a complementary RNA nucleotide sequence. The terminator specifies the end of transcription. The non-transcribed strand of DNA is called the coding strand.

Front 66

Translation

Back 66

information encoded in a portion of the mRNA to guide the ribosomes into making a polypeptide; entails the participation of m RNA, tRNA, translation factors, ribosomes and is energized by hydrolysis of GTP

Front 67

RNA

Back 67

single stranded, sugar: Ribose. DNA's thymine replaced in RNA with uracil

Front 68

mRNA

Back 68

transcription from nuclear DNA results first in pre-mRNA which is then processed into functionally active mRNA which moves from eukaryotic nucleus to ribosome in cytoplasm, now directing amino acid sequence for polypeptide assembly by rRNA

Front 69

tRNA

Back 69

intermediary between mRNA codon and an amino acid. Transports specific amino acids to ribosome and positions each amino acid at correct place on polypeptide chain.
45 in humans

Front 70

Aminoacyl-tRNA Synthetases

Back 70

catalyzes the attachment of amino acids to tRNA; one specific to each of the 20 amino acids

Front 71

rRNA

Back 71

found in ribosomes; polypeptides are assembled

Front 72

Bacterial RNA Polymerase

Back 72

binds the promoter region of a gene to a sigma factor during initiation of transcription. Synthesizes RNA. Catalyzes addition of nucleotides to 3' end of growing RNA strand. Dissociates from DNA at terminator

Front 73

RNA Polymerase II

Back 73

Eukaryotic enzyme that uses DNA as a template to make mRNA - initiates transcription

Front 74

Promoter

Back 74

Specific DNA Sequence at beginning of gene where RNA polymerase II binds to begin transcription

Front 75

TATA Box

Back 75

Core promoter

Front 76

RNA Synthesis

Back 76

Synthesized in 5' to 3' direction, moving along DNA in 3' to 5' direction

Front 77

Eukaryotic post-transcriptional modifications to pre-mRNA to produce mature mRNA

Back 77

takes place in nucleus;
splicosomes remove introns from primary transcript and reattach exon areas and other modifications occur.

methylated GTP to 5' end (cap)
Adenine Residues 3' tail

Front 78

Codons

Back 78

Blocks of information in the form of a sequence of three adjacent nucleotides in DNA or mRNA that codes for one amino acid

Front 79

64mRNA Codon Combinations

Back 79

4 different nucleotides
20 amino acids
Start: AUG
Stop: UAA, UAG, UGA,

Front 80

Principles for operation of genetic code

Back 80

1. all 4 nucleotide bases must be used
2. each combination of any 3 nucleotides can act as a codon
3. a particular codon found on mRNA, always specifies the same amino acid.

Front 81

Initiation Complex

Back 81

complex formed for initiation of translation
consists of the small ribosomal subunit; mRNA; tRNA with methionine and three initiation factors: initiation requires input of energy through GTP hydrolysis.

Front 82

tRNA

Back 82

each carries a specific amino acid to free, single-stranded -OH end of growing polypeptide chain.

Front 83

anticodon

Back 83

sequence on tRNA that is complimentary to a three-base sequence on mRNA

Front 84

aminoacyl-tRNA synthases

Back 84

activating enzymes that promote particular tRNA to become attached to specific amino acid

Front 85

A large ribosomal subunit

Back 85

where the tRNA anticodon binds to mRNA codon

Front 86

p site on the ribosome

Back 86

where the tRNA adds its amino acid to growing polypeptide chain via peptide bond

Front 87

e site on ribosome

Back 87

where tRNA goes before exiting ribosome

Front 88

components of protein synthesizing machinery

Back 88

mRNA, tRNA, ribosomes, initiation factors, amino acids.

Front 89

introns

Back 89

intervening sequences of non-coding DNA that upon being transcribed on pre-mRNA must be removed before mature mRNA code for protein synthesis.

Front 90

spliceosomes

Back 90

complex responsible for splicing, or removal, of introns

Front 91

Gene Regulation

Back 91

Cell's ability to control their level of gene expression

Front 92

Structural Genes

Back 92

Proteins only produced at a certain time and in specific amounts.

Front 93

Constitutive Genes

Back 93

Unregulated and have essentially constant levels of expression

Front 94

Functions achieved through regulation of gene expression

Back 94

Prokaryotes: can adapt to changing environments, so genes are grouped for common functions.
Eukaryotes: Development, homeostasis, function as a whole.
-genes are organized individually, regulated by small effector molecules - more complicated

Front 95

Cell Differentiation

Back 95

Leads to cells with the same genome, but with different proteomes (expressed proteins)

Front 96

Activators

Back 96

Bind to DNA to increase transcription or turn on a gene

Front 97

Transcriptional Control

Back 97

Most common mechanism for gene expression regulation

Front 98

Regulatory Proteins

Back 98

Possess DNA binding motifs that allow them to bind to bases of the DNA at the major groove.

Front 99

Effector Molecules

Back 99

Regulate gene transcription by binding a regulatory protein

Front 100

Operators

Back 100

Site immediately in front of promoter region; regulatory proteins can bind to this site to reduce or shut off transcription.

Front 101

Repressors

Back 101

Bind to DNA in vicinity of promoter and impose negative control by inhibiting transcription

Front 102

Enhancers

Back 102

DNA sequences to which specific transcription factors (control-proteins) bind to increase the rate of eukaryotic transcription

Front 103

Operon

Back 103

Cluster of functionally-related genes encoded into a mRNA molecule; a mode of prokaryotic gene regulating unit.

Front 104

Polycistronic mRNA

Back 104

mRNA that contains the coding sequence for two or more structural genes

Front 105

lac operon

Back 105

DNA Region that contains genes for use of lactose as an energy source. Contains 3 structural genes: lacZ, lacY, lacA STUDY TABLE 13.2

Front 106

Glucose vs. Lactose

Back 106

When presented with both, bacterial cells prefer to use glucose

Front 107

trp Operon

Back 107

5 gene cluster involved in the biosynthesis of trptophan

Front 108

mediator

Back 108

facilitates interactions between RNA polymerase II and regulatory transcription factors.
Controls the rate at which RNA polymerase transcribes mRNA

Hint 108

Partially wraps around RNA polymerase and the general transcription factors and is composed of several proteins.

Front 109

repressor

Back 109

protein that down-regulates transcription by binding to the operator

Front 111

Inducer

Back 111

Molecule that can inactivate a repressor protein by binding to it, thereby allowing transcription to proceed

Front 112

Core Promoter

Back 112

Site at the 5' end of a gene to which RNA polymerase attaches to initiate transcription; includes the transcriptional start site and TATA box

Front 113

Operator

Back 113

site of negative genetic regulation; binding by repressor blocks transcription

Front 114

CAP

Back 114

protein that initiates the transcription of genes, which allow the use of non-glucose molecules

Front 115

Inducer Exclusion

Back 115

Main form of glucose repression of the lac operon; high glucose levels cause low cAMP (inducer) levels.