Module 5.2 - Molecular Genetics

Front 1

Gene

Back 1

A DNA nucleotide sequence that carries the information needed to produce a specific RNA or polypeptide product

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Replication

Back 2

DNA is replicated (copied) in the S phase of the cell cycle so it can be passed on to offspring.

Process in which one DNA molecule is used as a template to produce additional DNA in the nucleus

Front 3

Transcription

Back 3

the synthesis of RNA molecules complementary to DNA

Front 4

Translation

Back 4

RNA becomes a coded template to direct polypeptide synthesis (synthesis of an amino acid)

Front 5

Rosalind Franklin

Back 5

used X-ray diffraction to determine 3-D structure and measurements of the DNA molecule (DNA is a double helix)

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Chargaff's Rule

Back 6

Base pairing. Bases can be purines or pydrimidines

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Purines

Back 7

Adenine and Guanine

Front 8

Pyrimidine

Back 8

Cytosine and Thymine

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Structure of a nucleotide

Back 9

5 Carbon Deoxyribose, A phosphate, and one of 4 nitrogenous bases

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Bond of nucleotides

Back 10

Phosphodiester bond to form a sugar-phosphate backbone

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The nitrogenous base attaches to...

Back 11

the 1' carbon of the sugar

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The phosphate attaches to...

Back 12

the 5' carbon

Front 13

The 3' carbon of one sugar bonds to the

Back 13

5' phosphate of the adjacent sugar to form a 3', 5' phosphodiester linkage

Front 14

Nucleoside triphosphates

Back 14

found in cells, as free molecules, serve as substrates for replication

Front 15

Mutations

Back 15

changes in the sequence of bases in DNA, which are reproduced in a new sequence of complementary bases during the next replication cycle

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DNA helicase

Back 16

unwinds 2 strands of double helix

Front 17

DNA gyrase

Back 17

relieves the tension created by the unwinding

Front 18

Nucleotide substrates

Back 18

align based on complementarity rules

Front 19

DNA polymerase

Back 19

adds free nucleotide subunits to the 3' end of the new chain

Front 20

Bonds that form between 2 separate nucleotides

Back 20

Hydrogen bonds

Front 21

Leading strand

Back 21

Synthesized continuously

Front 22

Lagging stranded

Back 22

Synthesized discontinuously

Front 23

Messenger RNA

Back 23

Carries the codons for the amino acid sequence in a polypeptide

Front 24

Transfer RNA

Back 24

Adaptor molecules that links amino acid to the mRNA codon

Front 25

Ribosomal RNA

Back 25

A globular form which is an important structural component of ribosomes. Each ribosome contains ribosomal RNA and many proteins. Assemble amino acids into protein chains

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Transcription

Back 26

the process during which a gene is used as the template to produce a piece of RNA

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When & Where does transcription occur

Back 27

In the nucleus and during G1 & G2 Phase

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RNA polymerase

Back 28

the enzyme that catalyzes phosphodiester bonds in RNA

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Initiation

Back 29

RNA polymerase and associated proteins initially bind to a promoter. Next, the DNA double helix is unwound and transcription is initiated

Front 30

Elongation

Back 30

Each nucleotide is added to the 3' end of the RNA molecule. Two phosphates are removed from a free nucleotide in an exergonic reaction. The remaining phosphate becomes part of the sugar-phosphate backbone.

Front 31

Termination

Back 31

occurs when RNA polymerase recognizes a termination sequence of bases in the DNA template.

RNA polymerase separates from the template DNA and the newly synthesized RNA

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Post-transcriptional modification of Eukaryotic mRNA

Back 32

5' cap (modified guanosine triphosphate) is added to the 5' end of the mRNA molecule.

Poly-A-tail (adenine-containing nucleotides may be added at 3' end of mRNA molecule)

Removal of introns (noncoding sequences) from pre-mRNA by spliceosomes (snRNPs, small nuclear ribonucleoprotein complexes)

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Introns

Back 33

Non-coding regions

Removed from original pre-mRNA

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Exons

Back 34

coding regions in eukaryotic genes

spliced to produce continuous polypeptide coding sequence

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Translation

Back 35

the process by which the mRNA sequence (triplets, codon) is translated into a polypeptide chain

Front 36

Codons

Back 36

Sequence of 3 mRNA nucleotide bases

(64 total, 61 codes for amino acids (including start signal AUG) and 3 stop signals)

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Wobble hypothesis

Back 37

the third nucleotide of a tRNA anticodon may sometimes form hydrogen bonds with more than one kind of third nucleotide of a codon.

"Wobble" results in several acceptable forms of base pairing between mRNA and tRNA

Front 38

Leader sequence

Back 38

non-coding sequence at the 5' end that has recognition sites to bind and position ribosomes for translation

Front 39

Transfer RNA

Back 39

carries the correct amino acid to the corresponding codon on the mRNA.

Each tRNA has a sequence of three bases (anticodons) that hydrogen-bonds with the mRNA codon by complementary base pairing

Front 40

Ribosomes

Back 40

site of translation

composed of 2 different subunits, each containing protein and rRNA

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3 steps of Translation

Back 41

Initiation, Elongation, Termination

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Anticodon

Back 42

the sequence of 3 nucleotides in the central loop/leaf of a tRNA molecule

Front 43

Specific locations within a ribosome

Back 43

A- Amino acid entry

P- Peptide bond formation

E- exit of use tRNA

Front 44

Missense mutation

Back 44

A nucleotide in one codon is altered and the new codon specifies a different amino acid

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Silent base substitution

Back 45

A nucleotide in one codon is altered but the new codon still specifies the same amino acid

Front 46

Nonsense mutation

Back 46

A nucleotide in one codon is different and the new codon becomes a stop codon

Front 47

Frameshift mutation

Back 47

insertion or deletion of one base in a gene

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Vector

Back 48

a carrier that can transport a DNA fragment to a desired location.

Front 49

A recombinant (hybrid) DNA molecule

Back 49

The combination of DNA fragment plus its vector

Front 50

Plasmid

Back 50

small, circular DNA molecule found in bacteria, used as a vector

Front 51

RNA interference (RNAi)

Back 51

involves small interfering RNAs, microRNAs, and other short RNA molecules

Front 52

Small interfering RNAs (siRNAs)

Back 52

help control damage from viral infections; and regulate gene expression of protein-coding genes

Front 53

microRNAs (miRNAs)

Back 53

inhibit expression of mRNA molecules with sequences complementary to the miRNA

Front 54

Restriction Enzymes

Back 54

make cuts in DNA based on very specific nucleotide sequences. Produces short DNA fragments

Front 55

Transformation

Back 55

the process of a plasmid being taken in by a host cells. When the host bacterial cell divides, the plasmid gets copied

Front 56

Cloning

Back 56

producing multiple copies of a gene. It occurs by inserting the DNA fragment containing the gene into a vector, then transformation and cell division of the host cell.

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DNA library

Back 57

a complete collection of all of the DNA fragments from one's genome

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DNA fingerprinting

Back 58

an analysis of the unique fragments produced by individuals

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Genomics

Back 59

the branch of molecular biology that looks at the complete genome, tracking the proteins produced and how the genes are regulated

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Bioinformatics

Back 60

the mathematical/computational analysis of the differences in genomes among members of a species (or among different species)