Chapter 11 Study Guide Flashcards
Mutagens are often called _________, agents that cause cancer
Carcinogens
Each amino acid is defined within the mRNA by a triplet of nucleotides called a
Codon
The mRNA is read in groups of 3 nucleotides
Codons
The codon _____ acts as a start codon
AUG
There are 3 stop codons
UAA
UAG
UGA
Whereas 61 of the 64 possible triplets code for amino acids, three of the 64 codons do not code for an amino acid; they terminate protein synthesis, releasing the polypeptide from the translation machinery. These are called the _________ ?
Stop codons or nonsense codons
Involves the exchange of DNA from one cell to another
Conjugation
Is an essential enzyme responsible for synthesizing new DNA strands during the process of DNA replication
DNA polymerase
Types of genes an individual carries (genetic makeup of an individual)
Genotype
Expressed genes observable characteristics of an individual based on genotype
Phenotype
DNA ➡️ RNA ➡️ protein ➡️ gives function
Central dogma of genetics
An enzyme called _____, then separates the DNA strands by breaking the hydrogen bonds between nitrogenous bases
Helicase
One strand is made in segments called Okazaki fragments (lagging strand) and are joined together with a
Ligase
Any inheritable change in the DNA is a mutation
Spontaneous mutations are caused by _______
Induced mutations are caused by ______
Replication errors
Mutagens
Are short segments of DNA formed on the lagging strand during DNA replication
Okazaki fragments
An _______ is a segment of DNA to which a repressor protein binds to regulate the expression of a set of genes, often part of the operon.
Operators
Are key elements in the regulation of gene transcription, controlling whether certain genes are turned on or off.
Operators
In bacteria and archea, structural proteins with related functions are usually encoded together within the genome in a block called an _____ and are transcribed together under the control of a single promoter, resulting in the formation of a polycistronic transcript
Operon
A _______ allows close contact between cells
A bridge forms between the cell
Pilus
A _____ is a specific region of DNA that acts as a starting point for gene transcription.
It’s where RNA polymerase binds to begin copying the genetic instructions into mRNA
Promoter
Is the process by which a cell copies its DNA to pass genetic information to the next generation of cells during cell division.
DNA replication
Is an enzyme that synthesizes RNA from a DNA template during the process of transcription
RNA polymerase
Refers to the twisting and coiling of DNA
Supercoiled
Is an enzyme that regulates the overwinding or under winding of DNA during the processes such as replication, transcription, and chromosome condensation.
Topoismerase
In ______, bacteria receive DNA via a bacteriophage
Transduction
In _______, naked DNA in the enviorment is taken up by the cell
Transformation
The DNA may be incorporated into the chromosome or remain as a plasmid in the cytoplasm
Transformation
During ______, a polypeptide chain is made using mRNA as a template
Translation
Also called “jumping genes”
Found in both prokaryotes and eukaryotes
May slo carry genes, such as for antibiotics resistance
Can insert themselves randomly into a chromosome
Transposons
Are segments of DNA that have the ability to move from one location to another because they code for the enzyme transposase
Transposons
What are the two essential functions of DNA ?
Replicate itself for cellular reproduction
Instruct the cell how to make the proteins it needs
The process of producing a protein through transcription and translation is called
Gene expression
Are all genes in a cell expressed at all times ?
No, cells can selectively express genes based on their needs, developmental stage, or environmental conditions
Genes that are always expressed are known as _______; known as housekeeping genes because they are necessary for the basic functions of the cell
Constitutive genes
Regulates genes ______ as needed
Turned on and off
Why is DNA replication described as semi conservative ?
Because each new DNA molecule formed consists of one original strand and one newly synthesized strand.
the location in the chromosome where DNA replication begins
Origin of replication
1 origin of replication, circular DNA
Multiple origins of replication, linear DNA
Prokaryote
Eukaryotes
Why are Topoismerases needed for replication ?
They prevent supercoiling
In what direction does replication occur ?
5’ ➡️ 3’
synthesized continuously in the same direction as the replication fork
synthesized discontinuously in fragments, moving opposite to the forks direction
Leading strand
Lagging strand
Synthesizes RNA primers needed to start replication
Primase
Short DNA fragments formed on the lagging strand
Okazaki fragments
What enzyme joins Okazaki fragments together
Ligase
In _______, the DNA polymerase reads the newly added base, ensuring that it is complementary to the corresponding base in the template strand before adding the next one
Proofreading
Introduces single stranded break into concatenated chromosomes to release them from each other, and then reseals the DNA
Topoismerase IV
Since the bacterial chromosomes are circular, a special enzyme is needed to separate the two daughter cells
Topoismerase IV
Is to copy a genes DNA sequence into RNA
Transcription
The _______ is a DNA sequence that serves as the binding site for RNA
promoter
Is found upstream before the gene near the 5’ end of the coding strand
Promoter location
Which enzyme is the key enzyme needed to produce mRNA
RNA polymerase
same sequence as RNA but with the T instead of U
Read by rna polymerase to make complementary rna
Coding strand
Template strand
During transcription which nucleotide pairs with adenine ?
Uracil
How does RNA polymerase “know” when it has reached the end of a gene?
Recognizes termination signals
What is the purpose of translation ?
Synthesize proteins from the mRNA template
What two types of RNA are needed for translation, in addition to mRNA
tRNA
rRNA
A ______ is a sequence of three nucleotides in mRNA that corresponds to a specific amino acid
Codon
There are 61 _______ that specify amino acids
Sense codons
There are 3 ________ that signal the termination of protein synthesis
Nonsense codons
Nonsense codons
UAA
UAG
UGA
There is 1 ________, which not only indicates the start of translation
Start codon AUG
All cells use the same decoder ring
Universal
Nucleotides are read in groups of 3
Triplet
Each nucleotide is only used once. Codons nerve overlap each other
Nonoverlapping
In ______, transcription and translation can occur at the same time.
In ______, transcription and translation are completed separately
Prokaryotes
Eukaryotes
Any inheritable change in the DNA is a
Mutation
Are caused by replication errors
Spontaneous mutations
Are caused by mutagens
Induced mutations
A _______ is any agent that causes changes in the DNA sequence of an organism
Mutagen
Mutagens are often called ________, agents that cause cancer
Carcinogens
A ______ is a change in a single nucleotide in the DNA sequence
Point mutation
An _______ is a mutation that involves the addition of one or more nucleotide bases into the DNA sequence
Insertion mutation
A ________ is a mutation that involves the removal of one or more nucleotide bases from the DNA sequence
Deletion
A _______ results in a different amino acid being incorporated into the resulting polypeptide
Missense mutation
A ________ converts a codon encoding an amino acid into a stop codon
Nonsense mutation
Caused by insertions or deletions of a number of nucleotides that are not multiple of three
Frameshift mutations
A point mutation will commonly result in the same amino acid being incorporated into the resulting polypeptide despite the sequence change. This change will have no effect on the proteins structure and is thus called a
Silent mutation
Genetic diversity can be achieved through
Horizontal gene transfer
Do all cells have operon ?
No, just prokaryotes
The ______ is a DNA sequence where regulatory proteins bind to control the transcription of the operon
Operator
Where is the operator found ?
It is located between the promoter and the structural genes of the operon
preventing transcription of the lac operon when lactose is absent
Repressor
In the absence of lactose, the lac repressor binds the operator, and transcription is
Blocked
In the presence of lactose, the lac repressor is released from the operator, and transcription proceeds at a
Slow rate