microbiology ch 8 Flashcards
What is genetics?
The study of genes, how they carry information, how information is expressed, and how genes are replicated
What is genetics also known as?
The science of heredity
What is a genome?
All the genetic information in a cell
What are genes?
Segments of DNA that encode functional products, usually proteins
What are chromosomes?
Structures containing DNA that physically carry hereditary information
What do chromosomes contain?
Genes
This is the study of genes, how they carry information, how information is expressed, and how genes are replicated; also known as the science of heredity
Genetics
This is all the genetic information in a cell
Genome
These are segments of DNA that encode functional products (usually proteins)
Genes
These are structures containing DNA that physically carry hereditary information
Chromosomes
What is the genetic code?
A set of rules that determines how a nucleotide sequence is converted to an amino acid sequence of a protein
What is the central dogma?
Sequence of nucleotides in DNA determine the sequence of amino acids in a protein
This is a set of rules determining how a nucleotide sequence is converted to an amino acid sequence of a protein
Genetic code
This says that the sequence of nucleotides in DNA determines the sequence of amino acids in a protein
Central dogma
What is a genotype?
The genetic makeup of an organism
What is a phenotype?
An expression of an organism’s genes
Does a genotype represent an organism’s potential properties?
Yes
Does a genotype represent an organism’s expressed properties?
No
This is the genetic makeup of an organism
Genotype
This is the expression of an organism’s genes
Phenotype
Does a phenotype represent an organism’s potential properties?
No
Do bacteria have a single circular chromosome made of DNA and associated proteins?
Yes
What are short tandem repeats (STRs)?
Repeating sequences of noncoding DNA
Do bacterial genomes contain back-to-back genes?
No
These usually have a single circular chromosome made of DNA and associated proteins
Bacteria
These are repeating sequences of noncoding DNA
Short tandem repeats (STRs)
What is vertical gene transfer?
The flow of genetic information from one generation to the next
What is horizontal gene transfer?
The transfer of genetic information between two organisms in the same generation
This is the flow of genetic information from one generation to the next
Vertical gene transfer
This is the transfer of genetic information between two organisms in the same generation
Horizontal gene transfer
What happens during DNA replication?
One parental double-stranded DNA molecule is converted into two identical offspring molecules
What is semiconservative replication?
When each double-stranded DNA molecule contains one original strand and one new strand
During this, one “parental” double-stranded DNA molecule is converted into two identical offspring molecules
DNA replication
This is when each double-stranded DNA molecule contains one original strand and one new strand
Semiconservative replication
What shape does a DNA molecule form?
Double helix
What does the ‘backbone’ of the DNA double helix consist of?
Deoxyribose-phosphate
How are the two strands of the DNA double helix held together?
By hydrogen bonds between A-T and C-G
What forms the genetic instructions of the organism?
Order of the nitrogen-containing bases
This forms a double helix
DNA molecule
This part of DNA consists of deoxyribose-phosphate
DNA ‘backbone’
These are held together by hydrogen bonds between A-T and C-G
Two strands of nucleotides in DNA double helix
This forms the genetic instructions of the organism
Order of nitrogen-containing bases
In DNA replication, what does one strand serve as?
A template for the production of a second strand
What two enzymes relax the strands in DNA replication?
Topoisomerase and gyrase
What enzyme separates the strands during DNA replication?
Helicase
What do topoisomerase and gyrase do during DNA replication?
Relax the DNA strands
What does helicase do during DNA replication?
Separates the DNA strands
What three roles does DNA polymerase have during DNA replication?
Adds nucleotides to growing DNA strand; removes RNA primers, joins Okazaki fragments (along with DNA ligase)
What direction does DNA polymerase go in during DNA replication?
5 –> 3’
What initiates DNA synthesis during replication?
RNA primer
Is the leading strand of synthesized continuously during DNA replication?
Yes
Is the lagging strand synthesized continuously during DNA replication?
No
What enzyme removes RNA primers?
DNA polymerase
What two enzymes join Okazaki fragments?
DNA polymerase and DNA ligase
What enzyme adds nucleotides to the growing DNA strand?
DNA polymerase
Does DNA polymerase add nucleotides to the growing DNA strand in a 3’ to 5’ direction?
No
How is the leading strand synthesized in DNA replication?
Continuously
Does synthesis of the lagging strand by DNA polymerase create Okazaki fragments?
Yes
How is the lagging strand synthesized in DNA replication?
Discontinuously
Does synthesis of the leading strand by DNA polymerase create Okazaki fragments?
No
Is the leading strand synthesized discontinuously in DNA replication?
No
Is the lagging strand synthesized discontinuously in DNA replication?
Yes
What are Okazaki fragments?
Sections of DNA synthesized on the lagging strand by DNA polymerase
What supplies the energy for DNA replication?
Nucleotides
What process provides energy from nucleotides for DNA replication?
Hydrolysis of two phosphate groups on nucleotides
What direction does most bacterial DNA replication go in?
Bidirectional
How many copies of the DNA molecule does each offspring cell receive?
1
What makes replication so accurate?
Proofreading capability of DNA polymerase
Is most bacterial DNA replication unidirectional?
No
Does each offspring cell receive 2 copies of the DNA molecule?
No
What does the proofreading capability of DNA polymerase ensure?
That replication is highly accurate?
What three components distinguish RNA from DNA
Single-stranded nucleotide; 5-carbon ribose sugar; Uracil instead of thymine
This molecule is made up of a single-stranded nucleotide, a 5-carbon ribose sugar, and uracil rather than thymine
Ribonucleic acid (RNA)
This form of RNA is an integral part of ribosomes
Ribosomal RNA (rRNA)
This form of RNA transports amino acids during protein synthesis
Transfer RNA (tRNA)
This form of RNA carries coded information from DNA to ribosomes
Messenger RNA (mRNA)
What is the function of ribosomal RNA (rRNA)?
Forms an integral part of ribosomes
What is the function of transfer RNA (tRNA)?
Transports amino acids during protein synthesis
What is the function of messenger RNA (mRNA)?
Carries coded information from DNA to ribosomes
What is transcription?
Synthesis of a complementary mRNA strand from a DNA template
When does transcription begin?
When RNA polymerase binds to the promoter sequence on DNA
What direction does transcription go in?
5 –> 3
How many DNA strands are transcribed by RNA polymerase?
1 of 2
When does transcription stop?
When RNA polymerase reaches the terminator sequence on DNA
This is the synthesis of a complementary mRNA strand from a DNA template
Transcription
RNA polymerase binding to the promoter sequence on DNA begins this process
Transcription
Are both DNA strands transcribed by RNA polymerase?
No
Does transcription proceed in the 5 –> 3 direction?
Yes
What happens when RNA polymerase reaches the terminator sequence on DNA?
Transcription stops
What is mRNA translated into?
The ‘language’ of proteins
What are codons?
Groups of three mRNA nucleotides that code for a particular amino acid
How many codons are there?
64
How many amino acids are there?
20
How many sense codons encode the 20 amino acids?
61
How many ‘nonsense’ or stop codons are there?
3
What is it mean that the genetic code involves degeneracy?
Each amino acid is coded by several codons (redundancy)
This is translated into the ‘language’ of proteins
mRNA
These are groups of three mRNA nucleotides that code for a particular amino acid
Codons