Chapter 8: Microbial Genetics study guide Flashcards
What are introns?
a segment of a DNA or RNA molecule which does not code for proteins and interrupts the sequence of genes.
what are exons?
regions of DNA expressed
what are snRNPs?
small nuclear ribonucleoproteins
remove introns and slice exons together to help form mRNA
which cell type uses introns, exons, and snRNPs? where exactly?
eukaryotes ONLY
within the nucleus
How is constitutive different from inducible enzymes?
What are the two types of nucleic acids?
DNA
RNA
What are the three parts of a nucleotide?
sugar
nitrogenous base
phosphate group
What are the four types of nitrogenous bases used in RNA?
A U C G
What are the four types of nitrogenous bases used in DNA?
A T C G
What are the enzymes given in class that are involved with DNA replication?
leading strand: DNA polymerase
lagging strand: DNA polymerase
RNA primase
DNA ligase
Describe the meaning of semiconservative replication.
the process by which DNA makes copies of itself, each strand, as it separates, synthesizing a complementary strand.
How is bacterial DNA replication different than eukaryotic DNA replication?
eukaryotic DNA replication consists of vertical gene transfer
bacterial DNA replication consists of horizontal gene transfer
How is an RNA nucleotide different than a DNA nucleotide?
DNA: deoxyribose sugar and is double helix
RNA: ribose sugar and is single strand
What are the four nitrogenous bases used to make RNA?
adenine, cytosine, uracil, and guanine
Know the three basic forms of RNA and what they do.
ribosomal RNA (rRNA)
transfer RNA (tRNA)
messenger RNA (mRNA)
What does ribosomal RNA (rRNA) do?
integral part of ribosomes
ribozyme which carries out protein synthesis in ribosomes
What does transfer RNA (tRNA) do?
transports amino acids during protein synthesis
What does messenger RNA (mRNA) do?
carries coded information from DNA to ribosomes
What is transcription?
When a portion of a DNA molecule is used to make mRNA molecule
Which polymerase is used in transcription?
RNA polymerase
what is the end goal of transcription?
DNA -> mRNA
Where does transcription occur in a prokaryote?
Cytoplasm
Where does transcription occur in a eukaryote?
nucleus
What is the enzyme that allows for transcription?
RNA polymerase
What is translation?
the process through which information encoded in messenger RNA (mRNA) directs the addition of amino acids during protein synthesis
mRNA –> Protein
Where does translation take place?
occur in cytoplasm and ribosomes of either eukaryotes/prokaryotes
What is a codon?
mRNA language includes groups of three nucleotides such as AUG, GGC, or AAA
What does degeneracy mean?
several codons can signal the same one amino acid
What is the first amino acid? What is the codon for this amino acid?
Methionine
AUG
What are the three stop codons? Why do these codons cause translation to end?
UAA
UAG
UGA
in order to signal end of protein synthesis
What are the possible results of base substitution (point mutation)?
missense mutation
nonsense mutation
frameshift mutation
What is a silent mutation?
change in DNA base sequence that causes no change
how does UV radiation cause mutations?
cause thymine dimers
What are three possibilities that would allow for a silent mutation?
- degeneracy of genetic code (might still code for the same amino acid)
- function of protein may not change if amino acid is non-vital portion of protein
- changed amino acid is chemically similar
What are the two major ways DNA can become mutated?
- base substitution
- chemical mutations
how does ionizing radiation cause mutations?
causes the formation of ions that oxidize nucleotides and break the deoxyribose phosphate backbone
how does UV radiation cause mutations?
cause thymine dimers
how does UV radiation cause mutations?
cause thymine dimers
What are some examples of enzymes that repair mutagen damage?
photolyases
separates thymine dimers
What is the baseline error rate for DNA polymerase?
1 in a million
What is the error rate once mutagens are added into the picture?
1 in a thousand
What is the difference between horizontal and vertical gene transfer?
Vertical gene transfer: transfer of genes from an organism to its offspring
Horizontal gene transfer: transfer of genes between cells of the same generation
Which type of gene transfer can humans do?
Verticle
Where does DNA come from in transformation?
Genes transferred from one bacterium to another as “naked” DNA
THis “naked DNA” can come from dead or lysed cells
Do cells need to be in contact for transformation?
does NOT require a living donor cell but only requires the presence of persistent DNA in the environment.
What is conjugation?
plasmids transferred from one bacterium to another
Do cells need to be in contact for conjugation?
- Requires cell-to-cell contact via sex pili
- Must be of opposite mating type
Which cell structure transfers the plasmid from one cell to the other?
via a pilus
What happens to the recipient cell after conjugation is complete?
cell now has a plasmid that it can also transfer to other bacteria
What is an Hfr cell?
high-frequency recombination cell
Hfr cells contain the F factor on the chromosome
What is transferred during conjugation with an Hfr cell?
part of the chromosome of Hfr cell
What happens to the recipient cell after conjugation is complete with a Hfr cell?
a recombinant F- cell results
What is transduction?
DNA is transferred from a donor cell
to a recipient via a bacteriophage
Transduction is the process by which a virus transfers genetic material from one bacterium to another
what does transduction require in order to happen?
bacteriophages
True or False
DNA replication is when a cell makes a genetically different new strand of DNA
False
DNA replication is the process by which the genome’s DNA is copied in cells
What is the ultimate goal of a bacterial cell (or any cell) going through transcription and then translation?
The goal of transcription is to make a RNA copy of a genes DNA sequence
which type of mutation is the worst kind and is also most common?
frameshift mutation
