Week 4 Lecture Flashcards by Loui Mojica

DNA was first discovered by

Frederick Miescher

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discovered that DNA contained phosphates, five- carbon sugars (cyclic pentose), and nitrogen- containing bases

Phoebus Aaron Theodore Levine

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discovered the helical structure by x-ray crystallography

Rosalind Franklin

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who described the three-dimensional structure of the DNA molecule in the 1950s.

James Watson and Francis Crick

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is a double helical chain of deoxynucleotide.

DNA (deoxyribonucleic acid)

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is a double strand twisted together, which many
scientists refer to as a “spiral staircase” (resembling the handrail, sides, and steps of a spiral staircase)

Helix

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A phosphate group (PO4)

Nucleotides

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(the carbons in the pentose are
numbered 1′ through 5′) sugar (deoxyribose), which makes up the “handrails and sides”

Cyclic five-carbon pentose

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A nitrogen-containing base, or the “steps,” either a

Purine and pyrimidine

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The two complementary sugar phosphate strands run in opposite directions (antiparallel)

3 to 5 or 5 to 3

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basic building blocks of DNA

Nucleotide

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attaches to the 5′ carbon of the sugar,

Phospate

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is attached to the 3′ carbon of the sugar.

Hydroxyl group

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are held together by hydrogen bonds.

Base

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Information contained in DNA is determined primarily by the pyrimidine sequence of letters along the

Staircase

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consists of a fused ring of nine carbon atoms and nitrogen

Purine

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What is two purines

Adenine (A) and guanine (G)

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Consists of a single ring of six atoms of carbon and nitrogen.

Pyrimidine

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What is the Three pyrimidines

Thymine (T), cytosine (C) and uracil (U)

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is also involved in the production of RNA.

DNA (deoxyribonucleic acid)

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In RNA, the nitrogenous base is

Thymine (T)

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Thymine is replaced by

Uracil (U)

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Single-stranded and short, not double stranded and long, and contains the sugar ribose, not deoxyribose

RNA (ribonucleic acid)

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means of amplifying specific DNA sequences and detecting very small numbers of bacteria present in a specimen.

Polymerase chain reaction technique

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are silent genes, expressed only under certain conditions.

Gene

are always expressed are constitutive.

Gene

are expressed only under certain conditions are inducible

Gene

The duplication of chromosomal DNA for insertion into a daughter cell.

Replication

The synthesis of ssRNA, by the enzyme RNA polymerase, using one strand of the DNA as a template.

Transcription

The actual synthesis of a specific protein from the mRNA code.

Translation

Refers to the synthesis of a protein

Protein expression

are polypeptides composed of amino acids.

Protein

A group of three nucleotides in an mRNA molecule that signifies a specific amino acid.

Codon

The triplet of bases on the tRNA that bind the triplet of bases (codon) on the mRNA

Anticodon

consists of a single, closed, circular piece of dsDNA that is supercoiled to fit inside the cell

Bacterial genome

Contains all the information needed for cell growth and replication

Bacterial genome

genes are specific DNA sequences that code for the amino acid sequence in one protein

One gene equals one polypeptide

Are self-replicating extrachromosomal dsDNA molecules.

Plasmid

pieces of DNA that are mobile and may jump from one place mobile and may jump from one place in the chromosome to another place in the chromosome to another place

Jumping gene

Simplest mobile piece of DNA is an

insertion sequence (IS) element.

It is approximately ______ base pairs long with inverted repeats on each end

1000 base pairs

that allows the element to pop into and out of DNA

transposase enzyme

Which contain many IS elements.

Bacterial genome

are related mobile elements that contain additional genes.

Transposons

often carry drug-resistance genes and are usually located in plasmids

Transposons

Changes that occur in the DNA code and often result in a change in the coded protein or in the prevention of its synthesis

Mutations

occur in bacteria at a rate of about 1 in 109 cells

Spontaneous mutations

Occur as the result of error during DNA replication at a rate of about

1 to 107 cells

Give a type of mutagens that is physical agents

UV rays, Ionizing radiation, X-rays, Visible light, and Heat

What type of mutagen is chemical agents

Alkylating agents, aCridine dyes, 5-Bromouracil, 2-aminopurine and Nitrous acid.

A method by which genes are transferred or exchanged between homologous (similar) regions on two DNA molecules, forming new combinations of genes on a chromosome

Genetic recombination

Uptake and incorporation of free or naked DNA into a bacterial cell

Transformation

Can be incorporated into the bacterial genome by recombination.

Transformation

Cells that take up naked DNA are referred to as

Being competent

The recipient bacterium must be competent to absorb the exogenous fragments of bacterial DNA.

Transformation

Transfer of bacterial genes by a bacteriophage from one cell to another.

Transduction

consists of a chromosome (DNA or RNA) surrounded by a protein coat.

Bacteriophage

When a phage infects a bacterial cell, it injects its genome into the bacterial cell, leaving the protein coat outside.

Transduction

The phage may then take a lytic pathway, in which the bacteriophage DNA directs the bacterial cell to synthesize phage DNA and phage protein and package it into new phage particles

Transduction

What phase Cell eventually lyses , releasing a new phage that can infect other bacterial cells.

Lytic phase

In some instances, the phage DNA instead becomes incorporated into the bacterial genome, where it is replicated along with the bacterial chromosomal DNA; in this state is known as

Lysogeny

the phage is referred to as

being temperate.

Transfer of genetic material from a donor bacterial strain to a recipient strain

Conjugation

Close contact is required between the two cells.

Conjugation

possesses a fertility factor (F factor) on a plasmid that carries the genes for conjugative transfer

Donor strain (F+)

The donor strain produces a hollow surface appendage called

Sex or conjugation pilus

Transfer of DNA then occurs

Conjugation

which binds to the recipient F− cell and brings the two cells in close contact.

Sex or conjugation pilus

Bacteria have evolved a system to restrict the incorporation of foreign DNA into their genomes.

Restriction enzymes

produced that cut incoming, foreign DNA at specific DNA sequences

Restriction enzymes

The main effect of is elements in bacteria is that when an is element inserts itself into the middle of a gene,

It disrupt and inactives the gene

Some mutations are silent because

Redundancy of protein synthesis

May be the result of a change in one nucleotide base (a point mutation) that leads to a

Change single amino acid within protein

May be the result of insertions or deletions in the genome that lead to

Disruption of gene and frameshift mutation

variations in the nucleotide sequence of a genome

Mutation

are those that result from an exposure to chemicals, UV rays, x-rays, or some other environmental agent.

Induced mutation

occur without any exposure to any environmental agent

Spontaneous mutation

Substitutions, also known as

Point mutation

are those mutations that affect a single base pair. One base is replaced by another

Substitution

refers to a purine or pyrimidine being replaced by a base of the same kind; for example, a purine such as adenine may be replaced by the purine guanine.

Transition substitution

refers to a purine being replaced by a pyrimidine, or vice versa; for example, cytosine, a pyrimidine, is replaced by adenine, a purine.

Transversion substitution

is when the substitution results in a codon for a different amino acid.

Missense mutation

occurs when the substitution results in the formation of a stop codon (UAA, UAG, UGA)

Nonsense mutation

result of the addition of a base

Insertion

removal of a base, also known as

Deletion

only one nucleotide is inserted or deleted. They shift the reading frame of the codons

Frameshift mutation