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128 Cards in this Set
- Front
- Back
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What is genetics (define)?
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Study of genes, genetic information, the expression of the genetic information, replication of genetic information and passing it to subsequent generations or other organisms.
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What are the double-stranded helix held together by?
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Hydrogen bonds
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DNA exists as what?
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double-stranded helix
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Nitrogenous "A" pairs with what to create a base pair?
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"T"
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Nitrogenous "C" pairs with what to create a base pair?
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"G"
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Nitrogenous "T" pairs with what to create a base pair?
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"A"
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Nitrogenous "G" pairs with what to create a base pair?
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"C"
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What is the "backbone", to which the bases are held together by, made of?
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Sugar & Phosphate
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Name the 4 bases in the DNA (full term)
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Adenine
Cytosine Guanine Thymine |
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Pertaining to the structure of the DNA strands; one DNA strand is _________ to the other?
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Anti-parallel
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Each strand of DNA has what 2 things on the end?
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5' phosphate
3' hydroxyl |
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What is a nucleotide?
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A section of a DNA strand that contains the following:
1. Sugar deoxyribose 2. Phosphate group 3. Nucleobase of either: - A (adenine) - T (thymine) - C (cytosine) - G (guanine) |
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What is the general term of a segment of DNA?
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Gene
(Chromosome -> DNA -> Gene -> Polynucleotides/Codon -> Nucleotides) |
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What is the sequence of a gene made of?
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Polynucleotides or codon
(Chromosome -> DNA -> Gene -> Polynucleotides/Codon -> Nucleotides) |
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How many base pairs are in bacteria (roughly)?
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1000
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What are 2 functions of a gene?
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- Code for synthesis of protein
- Control other genes |
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What is a chromosome?
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Structure that contains DNA
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What is the shape of bacterial DNA?
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Circular
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What is genomics?
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The molecular characterization of genomes
Layman's term: Each cell has genetic information contained in it that expresses a characteristic about that cell. So genomics will breakdown the information within the cell and distinguish what each genome is capable of doing. Example: West Nile Virus; genomics configured the genome to be.... A T C G C G C A T T A C (made up sequence) |
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What does bacteria also contain besides it's circular DNA?
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Plasmid
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What is genotype?
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Genetic composition of an organism -- entire DNA
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What is phenotype?
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Expression of the genes of what properties they produce (pigmentation, cultural characteristics, etc)
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What does the DNA do in bacteria, before cell division?
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Replicates
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What is semiconservative replication?
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Process of replication in which the newly developed double helix strand contains one original and one new (replicated).
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What is the replication fork?
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Point at which replication and separation occurs in DNA replication.
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What enzyme is used to synthesize the daughter and parental DNA strand together?
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DNA dependent DNA polymerase
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Before synthesizing the 2 new DNA strands together, what does DNA dependent DNA polymerase do?
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Proofreads and removes mismatched bases
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What is the statistical error of DNA replication, in regards to base pairing?
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1 out of 1010
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Gene expression involves what 2 steps?
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Transcription
Translation |
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What gene expression produces mRNA?
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Transcription
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Where is mRNA translated?
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Ribosomes
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How does mRNA differ than DNA?
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T (thymine) is replaced by U (uracil)
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Explain the steps to protein synthesis from a gene expression
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1. DNA
(Transcription) 2. mRNA (Translation) 3. Protein |
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What's another term for sense strand?
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Coding strand
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Whats another term for antisense strand?
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Template strand
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How many codons are there?
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64
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Of the 64 codons, how many are sense codons and what are they made of?
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61 - amino acids
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Of the 64 codons, how many are nonsense codons and what is it also referred to as?
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3 - stop codon
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True or false:
All codons are made up of amino acids. |
False - nonsense codons aka stop codons are not amino acids.
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Which of the 2 strands (sense & antisense) is used for transcription of RNA?
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Antisense
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During transcription, what enzyme synthesizes a strand of mRNA and to which strand does it synthesize it from?
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DNA dependent RNA polymerase synthesizes from the antisense strand
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What is a term for a synthesized strand of mRNA from DNA?
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Template
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Where does transcription occur in prokaryotes?
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Cytoplasm
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Where does transcription occur in eukaryotes?
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Nucleus
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What does RNA stand for?
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Ribonucleic Acid
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What is the RNA nucleotide composed of?
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- Sugar ribose
- Phosphate group - A - C - G - U replaces T |
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Which direction is RNA synthesized/read and which strand does it transcribe from?
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5' ----> 3' Antisense
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What is the term for the starting point of transcription and what is codon that initiates this sequence?
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Promoter site - AUG
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What is a promoter site and where is it located on DNA?
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Starting point of transcription and its located on the sense strand.
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Term in which describes a region of DNA that is the endpoint of gene transcription.
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Terminator site
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What is translation?
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The process of assembling a protein (which is consisted of specific amino acid sequence), based off of the nucleotide sequence of mRNA
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Where does translation occur in both prokaryotes and eukaryotes?
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Cytoplasm
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Where does mRNA get translated and what is it consisted of?
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Ribosomes - rRNA & protein
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What is the role of tRNA and what does it contain to compliment the mRNA?
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Transfers specific amino acids to the ribosomes and contains ANTICODONS that compliment the codons of the mRNA
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What is a codon made up of?
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3 nucleotides aka trinucleotide
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Which amino acid translates from AUG?
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N-Formylmethionine or methionine
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Out of the 64 codons available, how many amino acids can be created?
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20
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Define degeneracy and what does it prevent?
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Allows for several codons to create a certain amino acid.
This allows for slight mistakes/mutation to occur but ultimately still creates the same amino acid. |
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What is genetic code?
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Is the relationship between codons and what amino acid it will produce in a certain sequence; ultimately forming a specific protein.
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Where are specific amino acids located on the tRNA?
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Acceptor arm
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What is an anticodon and where is it located?
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An anitcodon is complimentary to the codon found on the base of tRNA.
Layman's term: mRNA contains 3 nucleotides (A,U,C) which are called codons. The tRNA contains opposing codons called "anticodons" (T,A,G). anti = opposite |
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What is the primary role of ribosomes?
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Protein synthesis
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Translation ends when it reaches what?
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Stop codon or nonsense codon
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In prokaryotes when does translation begin?
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Translation in prokaryotes, begin before transcription completes.
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What are 2 ways gene expression is regulated?
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1. Protein is synthesized only when needed and is usually triggered
2. Constitutive enzymes are created at a fixed rate (e.g. enzymes for glycolysis) because of its' continual use. |
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What is repression and how is it triggered?
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Regulatory mechanism that inhibits gene expression triggered by an overabundance of end products
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What is Induction and how is it triggered?
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The process of turning on transcription triggered by molecules needed to be broken down (inducer)
Example: Presence of lactose will "induce" the production of the enzyme to breakdown lactose |
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What is the regulatory protein that inhibit gene expressions?
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Repressors
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Generally speaking, what starts an induction?
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Inducer
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What type of genes are turned on all the time?
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Constitutive genes
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What is lac operon?
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A series of genes responsible for the utilization of lactose;
lac = lactose Operon = "factory"; a set of structural genes that specify a specific protein/enzyme |
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True or false:
Lac operons are usually turned off. |
True
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What is an inducible operon?
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Inducible = potentially turned on
Operon = "factory"; a set of structural genes that specify a specifc enzyme Combination: An operon that can be turned on or off and potentially make a specific protein. It all depends on the presence of an inducer |
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What is mutation?
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Change in nitrogenous base sequence of DNA
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In general, mutations can be what?
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Neutral (silent
Disadvantageous/lethal Beneficial |
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What happens in a silent mutation?
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When a nucleotide on a DNA is substituted with another, but still creating the SAME AMINO ACID
Normal: AAT = UUA Mutation: AAC = UUG UUA & UUG are both the same codon for Leucine |
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Name the types of mutations
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1. Base substitution
a. Missense mutation b. Nonsense mutation 2. Frameshift mutation a. Addition mutation b. Deletion mutation 3. Spontaneous mutation 4. Induced mutation |
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What 2 types of mutation can occur in a base substitution?
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Missense mutation
Nonsense mutation |
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What occurs in a base substitution?
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At one point in the DNA sequence, a base pair was MISMATCHED; during DNA replication, it results in a substituted base pair.
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What happens in a missense mutation?
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Base substitution that results in the production of a different amino acid
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What happens in a nonsense mutation?
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Base substitution that results in the production of stop codons
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What happens in frameshift mutation and what are 2 subtypes of this mutation?
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One or a few base pairs are deleted or added to DNA
Addition mutation - shift right Deletion mutation - shift left |
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What is spontaneous mutation?
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Mutation in which occurs naturally because of copying errors during cell division
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What are mutagens?
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Agents in environment that cause permanent changes in DNA.
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What are 3 types of mutagens?
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Chemical mutagen
Ionizing radiation Ultraviolet radiation (non-ionizing) |
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What is a way to create a base substitution or a breakage of the sugar-phosphate backbone?
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Ionizing radiation
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What is a thymine dimer and how is it caused?
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A pair of abnormally chemically bonded adjacent thymine bases together caused by ultraviolet radiation.
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What can repair thymine dimers?
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Light-repair enzymes in the presence of visible light
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What is the mutation rate?
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Probability that a gene will mutate when a cell divides
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How often does spontaneous mutations occur?
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10 to the -6th
1/1000000 1 out of a million |
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Spontaneous mutation is beneficial because...?
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provides GENETIC DIVERSITY
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Describe an altered phenotype.
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A mutation that results with a different characteristic.
Example: Penicillin resistant cells |
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What are 2 methods to test for an altered phenotype?
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Positive (direct) selection
Negative (indirect) selection |
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Explain the positive (direct) selection method of testing for an altered phenotype.
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Selection of mutant cells by rejecting the nonmutated cells
Example: testing for penicillin resistant bacteria; by plating bacteria in a culture in penicillin, it can be identified DIRECTLY |
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Explain the negative (indirect) selection method of testing for an altered phenotype.
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The selection of mutant cells who cannot perform a certain function of its original function
Example: Testing for bacteria that cannot synthesize tryptophan (when they normally can) |
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What's a method of negative (indirect) selection?
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Replica plating
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Define auxotrophs
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A mutant that does possess the abilities of the parent cell.
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What is the ames test?
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Test to identify possible carcinogens
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True of false:
A mutant cell can revert to a normal cell in the presence of a mutagen |
True
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True or false:
Many mutagens are not carcinogens |
False
Many ARE carcinogens |
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What term is used to describe a mutant changed to the nonmutant state because of a carcinogen
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Reversions
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What is genetic recombination?
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Exchange of genes between 2 DNA molecules
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What term is used to describe the result of a new DNA from genetic recombination?
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Recombinant DNA or rDNA
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In genetic recombination, what term is used when 2 related chromosomes align, break, and rejoin,
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Crossing over
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Describe Vertical gene transfer
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Genes are passed from an organism to offspring
Example: plants and animals |
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Describe Horizontal gene transfer
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Genes are not only passed to offspring, but to other of the same generation as well.
Example: bacteria |
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A recombinant cell receives or donates DNA and what is the DNA called then-after?
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Receives - rDNA
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Name the process in which a cell lysis and the "naked" DNA of that dead cell is picked up by another cell.
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Transformation
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What was the 1st bacteria to be observed, that performed doing transformation?
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Streptococcus pneumoniae
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During conjugation, what components are needed for this to be done?
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2 living bacterial cells connected by a pilus.
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During conjugation, what does the symbol F+ represent?
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Genetic donor
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During conjugation, what does the symbol F- represent?
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Recipient
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F+ contain what type of circular DNA?
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Plasmids - F (fertility) factors
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F+ plasmid is also referred to as what?
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F (fertility) factors
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What does Hfr stand for?
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High-frequency recombinant
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Hfr cells contains F plasmids where in the cell?
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F plasmids are incorporated into their chromosomes
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When an Hfr cell conjugates with a F-, what does the F- become?
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It's labeled as a recombinant F-
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How does transduction occur?
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DNA is passd from one bacterium to another via bacteriophage
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In this type of transduction, any bacterial genes can be transferred
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Generalized transduction
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Define plasmids
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Closed circular extrachromosomal DNA that are self replicating.
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True or false:
A bacteria cannot survive without their plasmid. |
False - They CAN survive
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What 2 types of plasmids are there?
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Conjugative plasmids
Resistant plasmids |
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What types of genes do resistant plasmids carry?
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Genes for antibiotics or heavy metals resistance
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What are transposons?
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"jumping genes"; segments of DNA that jump from one region to another of the same chromosome, one region to a different chromosome, or one region to a plasmid
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What is a complex transposons?
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A gene that jumps from one place to another carrying a specific attribute (antibiotic resistance) and the gene mechanism that allows it to move from one chromosome to another.
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Natural selection allows what?
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Allows the growth of the best adapted for a given environment
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Diversity of organisms is described as what 2 terms?
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Genetic mutation & recombination
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True or false:
Diversity is the precondition of evolution |
True
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