Microbiology Chapter 9 DNA

Genetics

The study of heredity

Genetics

The study of the nature and function of genes

Gene

The unit of heredity

Gene

A segment of DNA that encodes a functional product

rRNA, tRNA

In addition to proteins a functional product of a gene could be _________ or __________.

Genome

All the genetic material in the cell

One

Typically, the bacterial genome contains _______ circular chromosome(s).

Nucleotide

What is the monomer of DNA?

Phosphate, 5-carbon sugar, and a nitrogenous base

What are the three subcomponents of a nucleotide?

Guanine and Adenine

Which nitrogenous bases are the purines?

Cytosine and Thymine

Which nitrogenous bases are the pyrimidines?

Adenine, Guanine, Cytosine, and Thymine

What are the four nucleotides in DNA?

2

How many hydrogen bonds form between the nitrogenous bases adenine and thymine?

3

How many hydrogen bonds form between the nitrogenous bases cytosine and guanine?

Hydrogen Bonds

What type of bond is formed between the nitrogen bases in nucleotides?

Phosphodiester Bond

What type of bond is formed between the phosphate group and deoxyribose sugar in DNA?

Weak

The hydrogen bonds between nitrogenous bases are relatively __________ and easily breakable.

Phosphodiester Bond

This type of bond is formed between the phosphate group and the 5-carbon sugar. It is a covalent bond that is high energy and difficult to break.

3’ and 5’

The phosphate group joins the ____ and the ______ carbons of sugars.

Double Helix

DNA is a _________ _____

Conserved

The structure of DNA is highly ____________ among the domains.

Phosphodiester

The sugar phosphate backbone of DNA is held together by _________________ bonds.

Hydrogen

The two strands are held together by weak __________ bonds between the nitrogenous bases.

Complementary

The hydrogen bonds form between ________ base pairs.

Antiparallel

DNA is arranged in an __________ arrangement.

Circular

Prokaryotes like bacteria have a ______________ chromosome but it still has the double stranded antiparallel arrangement.

Semiconservative

DNA replication is __________ meaning that a new DNA molecule has one strand from the original copy and one new strand.

Template

The old strand of DNA is a _______ for synthesis of the new strand.

Origin of Replication

The starting point of DNA replication

One

Prokaryotes usually have _________ origin of replication

Origins of Replication

Eukaryotes may contain multiple ___________ of replication along the chromosome.

Helicase

The enzyme that “unzips” DNA or separates the two strands at the replication fork

Single Stranded DNA binding Protein

Proteins that bind onto a single strand and stabilize the replication fork.

Replication Fork

The location where the two strands are split apart to open up the DNA for replication.

Primase

The enzyme that synthesizes RNA primers to allow for DNA replication.

Primers

RNA sequences complementary to DNA sequences. They function to assist DNA polymerase III in binding and beginning synthesis.

Double

DNA polymerase can only bind to ______________-stranded nucleic acids.

DNA polymerase III

The enzyme that is responsible for synthesis of the new strand of DNA by adding new complementary nucleotides.

3’ to 5’

DNA polymerase always reads______ on the template strand

3’

DNA polymerase III always adds nucleotides 5’ to 3’ on the new strand. (adds to the ____ end)

High-energy

The phosphodiester bond is very _______________ meaning that it also takes a lot of energy to synthesize.

Continuous

The leading DNA strand allows for _______________ DNA synthesis

Leading

When synthesizing the __________________ strand DNA pol III can follow directly behind helicase and only needs one RNA primer

Discontinuous

The lagging strand of DNA requires ___________ synthesis.

Leading

In the _____ strand DNA polymerase III can synthesize towards opening of the replication fork

Okazaki Fragments

In the lagging strand DNA polymerase III must synthesize new DNA in segments called _________________.

Lagging

In the ________ strand DNA polymerase III must synthesize away from the opening of the replication fork

Lagging

In the _____ strand multiple RNA primers are needed and the new strand is synthesized in fragments

DNA polymerase I

The enzyme that removes the RNA nucleotides from the RNA primer.

DNA ligase

The enzyme that seals the gaps between the Okazaki fragments to make a continuous strand of DNA.

Quickly

DNA replication in bacteria occurs very __________.

2

Prokaryotes have one origin of replication but have _________ replication forks that move away from each other until the complete new DNA molecule has been synthesized and they meet at termination.

Methylation

When an enzyme adds methyl groups to newly synthesized DNA molecules.

Expression

Methylation regulates gene ________________

Protection

Methylation is important for DNA ____________ as the cell degrades unmethylated molecules (viral DNA unmethylated so it is easy to attach)

Repair

Methylation is important for DNA ___________ because the original/older strand is methylated so mismatched repair enzymes use the older, methylated strand as a template to fix replication errors.

Cytosine

Which nucleotide is methylated?

False; only a select set of genes are actively expressed

True or false: All genes are expressed in a functional cell

Genotype

What genes (alleles) are present

Phenotype

The outward manifestation or presentation. This is influenced by gene expression

Phenotype

The DNA is related to genotype whereas the end product (proteins) is related to _____________

Phenotype

The end product proteins affect __________ because they are what influences metabolism and structure within the cell.

DNA → mRNA → Protein

Central Dogma

Transcription

The process from DNA → mRNA

Translation

The process from mRNA to proteins

mRNA

Which is the most common type of RNA?

Functional RNA

RNA that is not translated to proteins rather carry out a task in their RNA form. They are primarily used in the mechanisms of translation.

rRNA and tRNA

What are the two main types of functional RNA?

Single

RNA is _______-stranded

Ribose

Ribose contains the 5 carbon sugar ________

uracil

Which base does RNA have instead of thymine

Oxygen

Deoxyribose has one less _____ than ribose

RNA polymerase

The enzyme that synthesizes RNA using DNA as a template

Promoter

The regulatory sequence upstream from the coding sequence (gene) where RNA polymerase binds.

Initiation

The stage of transcription where RNA polymerase binds to the gene at the promoter region.

Elongation

The stage of transcription where RNA polymerase adds RNA nucleotides to make a mRNA transcript.

Termination

The phase of transcription where the mRNA molecule is finished and released.

Initiation

The phase when RNA polymerase interacts with sigma Factor and these molecules recognize and bind to the promoter.

Sigma factor

A protein subunit that interacts with RNA polymerase and helps recognize the promoter

Sigma factorFactor

A protein subunit required for transcription initiation

Sigma factorFactor

Because this protein subunit is required for transcription initiation, it can control its genes are being expressed and only it transcribe genes when needed

Promoters

Different sigma factors can bind to different_______

False some bacteria only have one but some have many

One true or false: bacteria only have one sigma factor

Gene expression

The presence of sigma factors can tailor _____ ______ to conditions

Elongation

The stage where RNA polymerase extends the transcript

3’ to 5’

Both RNA polymerase and DNA polymerase read DNA in the_______ direction

5’ to 3’

Both RNA polymerase and DNA polymerase add nucleotides in the ___________ direction

Phosphodiester

Both RNA polymerase and DNA polymerase synthesize ______ bonds between nucleotides

Rna polymerase

The enzyme that extends the mRNA transcript. It forms phosphodiester bonds between the nucleotides and adds uracil, adenine, guanine and thymine nucleotides

Sigma Factor

When elongation begins the_______ leaves

Template strand

What strand of DNA does RNA polymerase add nucleotides to

Uracil

Does RNA polymerase add uracil or thymine bases

Ribose

Does RNA polymerase add nucleotides with ribose or deoxyribose sugar

RNA polymerase

The enzyme that adds nucleotides to the MRNA transcript and does not need primers

RNA polymerase does not need a RNA primer and it unzips DNA by itself

How does RNA polymerase differ from DNA polymerase in how it synthesizes mRNA

DNA

Rna polymerase is able to unzip the _____ by itself and does not require helicase

Self-termination

The mechanism of termination in which transcription of a GC Rich Terminator region produces a hairpin loop which creates tension loosening the grip of polymerase on the DNA

2

How many mechanisms are there for termination

Termination

The stage where mRNA is completed and released

Terminator region

The region on DNA that signals for an end of transcription