Chapter 7 Flashcards
What is the structure of nucleotides
Nucleotides
- Deoxyribose sugar
- Nitrogenous base pairs
- Phosphate group
What is DNA replication?
– Replication is semi conservative
• New DNA composed of one original and one daughter strand
Key to replication is complementary base pairing of the two strands, which gives the template concept.
What enzymes are involved with Strand Seperation in DNA replication and what is their role?
Strand separation
Helicase- Unzips hydrogen bonds between nucleotides
Topoisomerases- Keeps strands from becoming tangled by releasing tension ahead of helicase
What enzymes are involved with Building New Strands in DNA replication?
Building new strands
RNA primase -Produces pieces of RNA that act as an anchor for DNA polymerase III
DNA polymerase III- Makes the bulk of the replicated DNA
DNA Polymerase I – removes/replaces RNA primers with segments of DNA
DNA ligase-Binds Okazaki fragments into one strand
What is a gene?
Gene - specific sequences that that code for a protein.
What are the nitrogeneous base pairs?
(guanine, cytosine,
thymine, adenine, or uracil)
DNA:
- C - G
- G-C
- T-A
- A-T
RNA
- C- G
- G-C
- U-A
- A-U
What are nucleotides and what do they consist of?
Nucleotide- monomer of nucleic acids
consists of three parts :
(1) phosphate (PO4);
(2) a pentose sugar, either deoxyribose or ribose
(3) one of five cyclic (ring-shaped) nitrogenous bases: adenine (A), guanine (G), cytosine (C), thymine (T), or uracil (U) (
What occurs in the nucleoid region?
transcription
What are the different types of plasmids?
– Fertility factors
– Resistance factors
– Bacteriocin factors
– Virulence plasmids
What are plasmids?
- Small loops of DNA that replicate independently
- Optional, not essential for normal metabolism, growth, or reproduction
- Can confer survival advantages
What is the leading strand?
The leading strand forms during DNA replication.
leading strand is synthesized continuously—
5’ to 3’—as a single long chain of nucleotides.
What is a Deoxyribose?
a pentose sugar which is found in deoxyribonucleic acid (DNA), or the nucleotides to be more specific
What is a genotype?
The genotype of an organism is the actual set of
genes in its genome.
What is a phenotype?
Phenotype refers to the physical features and functional traits of an organism, including characteristics such as
structures, morphology, and metabolism.
For example, the shape of a cell, the presence and location of flagella, the enzymes and cytochromes of electron transport chains, and membrane receptors that trigger chemotaxis are all phenotypic traits.
What is the central dogma of genetics?
The central dogma of genetics states that genetic information is transferred from DNA to RNA to polypeptides, which function alone or in conjunction as proteins.
What is transcription?
Information in DNA is copied as RNA
What is translation?
• Proteins (polypeptides) are synthesized from RNA
What are codons?
set of 3 bases on mRNA that corresponds to each DNA triplet. Each codon signals for a particular amino acid.
- If Template DNA triplets are:
3’ ATG CTT AAC CGG 5’
- Then the mRNA codons will be:
5’ UAC GAA UUG GCC 3’
What are anticodons?
Anticodons are triplets at the bottom of the tRNA loop. Anticodons are complementary to mRNA codons, and each acceptor stem ( which is on tRNA) is designed to carry one particular amino acid.
Where is the site of protein synthesis?
ribosomes
What is DNA replication?
DNA replication is an anabolic polymerization process that allows a cell to pass copies of its genome to its descendants.
-Key to replication is complementary base pairing of the two strands, which gives the template concept.
Describe an inducible operon
Inducible operons are not usually transcribing and must be activated by inducers
Ex: Lactose operon, Arabinose operon (lab)
Describe repressible operons
Repressible operons are transcribed continually until deactivated by repressors
Ex: Tryptophan operon
What is a mutation?
A change in the nucleotide base sequence of a genome
– Rare event
– Almost always deleterious
What is a mutagen?
Physical or chemical agents called mutagens that induce mutations
What is a bacteriophage?
A virus that infects bacteria
-they reproduce in bacteria
What is conjugation pili and what do they do?
Thin, proteinaceous tubes extending from the surface of a cell
Conjugation pili mediate the transfer of DNA from one cell to the othervia a process termed conjugation
What is a lagging strand?
a new
strand formed during replication that is synthesized 5’ to 3’ but in short segments that are later joined
What does triplet refer to when taling about DNA, RNA, or tRNA?
triplet sequence of nucleotides
What is a competence cell
Cells that have the ability to take up DNA from their environment
Competence results from alterations in the cell wall and cytoplasmic membrane that allow DNA to enter the cell.
What is tRNA
A transfer RNA (tRNA) molecule is a sequence
of about 75 ribonucleotides that curves back on itself to form three main hairpin loops held in place by hydrogen bonding between complementary nucleotides.
What is mRNA?
Messenger RNA molecules carry genetic information from chromosomes to ribosomes as triplet sequences
of RNA nucleotides (codons) that encode the order of amino acid sequences in a polypeptide.
What are the roles of DNA?
- Replication
- Cell division
- Need accurate copy
- Gene expression
- DNA
- RNA
- Protein
What is protein synthesis
Process in wich cells build proteins.
DNA is simply a set of instructions on how to make proteins.
DNA tells you which amino acids to use, and in what order to assemble those amino acids to produce thecorrect protein.
What are operons?
special arrangements of prokaryotic genes that play roles in gene regulation
They consists of a promoter, a series of genes that code for enzymes and structures such as channel proteins needed in response to changed environmental conditions, and an adjacent regulatory element called an operator
Describe point mutations
– Point mutations
- Most common
- One base pair is affected
- Insertions, deletions, and substitutions
Describe frameshift mutations
Frameshift mutations
- Nucleotide triplets after the mutation are displaced
- Insertions and deletions
Describe silent mutation
Some base-pair substitutions produce silent mutations because the substitution does not change the amino acid sequence due to the redundancy of the genetic code
For example, when the DNA triplet AAA is changed to AAG, the mRNA codon will be changed from UUU to UUC; however, because both codons specify phenylalanine, there is no change in the
phenotype—the mutation is silent because it affects the genotype only
Describe a missense mutation
A change that specifies a different amino acid is called a missense mutation; what gets transcribed and translated makes sense, but not the right sense. T
Describe nonsense mutations
mutation occurs when a base-pair substitution changes an amino acid codon into a stop codon.
Nearly all nonsensemutations result in nonfunctional proteins.
Describe radiation of a mutagen
– Xray/gamma ray (ionizing) causes electrons to excite which can cause covalent bond breakage of the sugar phosphate backbone of DNA
– UV (nonionizing) causes pyrimidine dimers (covalent bonding) warping the shape of DNA.
Describe nucleotide analogs
These compounds look like normal nucleotides, and when available may be erroneously substituted for nucleotides.
– Can be useful antiviral or anticancer drugs due to heightened replication of these cells.
What are the three types of chemical mutagens
- Nucleotide Analogs
- Nucleotide-Altering Chemicals
- Frameshift Mutagens
What is conjugation?
Conjugation – primitive “mating” between bacteria
Describe transformation
DNA exits one cell, taken up from the environment by another cell
Artificially induced in laboratory
- Cells that take up DNA are termed “Competent”
- useful tool for recombinant DNA technology
what is transduction
horizontal gene transfer, called transduction,
involves the transfer of DNA from one cell to another via a replicating virus
Transduction – Bacterial DNA transferred from one bacteria to another via a bacteriophage
What is a Base substitution mutation
type of mutation involving replacement or substitution of a single nucleotide base with another in DNA or RNA molecule.
What happens in horizontal gene transfer?
Donor cell contributes part of genome to recipient cell
What are the 3 types of horizontal gene transfer
- • Transformation
- • Transduction
- • Bacterial conjugation
Define Transduction in regards to horizontal gene transfer
Transduction – Bacterial DNA transferred from one bacteria to another via abacteriophage
A bacteriophage Is a virus that infects bacteria
Chapter Critical thinking questions:
Pgs: 197, 205, 209, 212, 216, 221, 233
Questions for practice from the back of the chapter:
Multiple choice:
2, 5, 8, 11, 12, 13, 15, 16, 17, 19, 20, 22, 23, 25
Fill in the blanks:
2, 3, 4, 7, 8, 11
Short answer 12 “fill in the table”
Labeling activity
Concept mapping activity
have fun :)
