Mod 3 Microbial Genetics Flashcards
The study of heredity
Genetics
Sum total of genetic material within a cell
Genome
Genome of cells is made up of
DNA
Genome of viruses is made up of
DNA or RNA
mode of gene transfer in which DNA is taken up by cell and incorporated into it’s genome
Transformation
units of DNA that contain the genetic information
Genes
Gene Expression
begins with transcription, leading to translation and conformation
Nucleoside
nitrogenous base + pentose sugar
Nucleotide
nucleoside + phosphate groups
In a eukaryotic cell the genome is made up of DNA information found in
The nucleus, chloroplasts, and mitochondria
In a prokaryotic cell the genome is made up of DNA information found in
Plasmids
Condensed, tightly wrapped form of the DNA molecule
Chromosome
Shape of chromosomes for prokaryotic (eubacteria) cells
Single circular loops
Shape of chromosomes for eukaryotic cells
Multiple and linear ( open on the ends)
Two researchers who played a critical role in establishing that DNA is the genetic material
Fred Griffith (early 1900s) & Oswald Avery (mid 1900s)
Discovered that non-pathogenic heat killed smooth strain and non-pathogenic rough cells combined to cause an infection
Fred Griffith
Refined Griffith’s transformation experiments to show that DNA was the genetic material being transferred
Oswald Avery
Two main themes of the Central Dogma of Biology
- DNA Replication
2. Gene Expression
fundamental units of heredity that are responsible for a given trait
genes
site on the chromosome that provides information for a certain cell function
genes
genetic sequence of the DNA of a particular organism
Genotype
physical expression of the genes; observable/measurable traits
Phenotype
Genome size of a virus
4-5 genes
Prokaryotic genome size - ex. E.coli
4,288 genes
Genome size of Human cells
31,000 genes
Two types of nucleic acids
DNA & RNA
Structure of a Nucleotide (3 parts)
- Purine or pyrimidine base (nitrogen containing)
- Ribose or deoxyribose (5 carbon sugar group)
1 & 2 } form Nucleoside of deoxynucleoside and
combine with - Phosphoric acid
Nucleoside =
nitrogenous base + pentose sugar
Nucleotide =
nucleoside + phosphate group
2 groups of Nitrogenous bases in DNA structure
Purines & Pyrimidines
Adenine & Guanine
Purines of DNA
Thymine & Cytosine
Pyrimidines of DNA
5 carbon sugar that is deoxygenated on carbon #2
Deoxyribose
alternate with pentose sugars to form the backbone of DNA structure
Phosphate groups
Individual nucleotide are connected together by ______ which are a type of ______.
phosphodiester bonds; covalent bond
two complementary strands of the repeating phosphate/pentose sugar + nitrogenous base structure form a
double helix
Describes that one strand of the double helix is situated in the 5’-> 3’ while the other is 3’ ->5’
Antiparallel
Base pairing rules
A with T: 2 hydrogen bonds
G with C: 3 hydrogen bonds
Adenine only pairs with ____
Thymine
Guanine only pairs with ____
Cytosine
Nitrogenous base attaches to the
1 Carbon
Phosphate groups attach to
3 & #5 Carbons
What is the complement to the following strand of DNA? 5’ - TTGCTAAGG - 3’
3’ - AACGATTCC - 5’
OR
5’ - CCTTAGCAA - 3’
* Must denote orientation*
An organism with 1000 nucleotide base pairs in it's genome was found to contain 100 Adenine bases. How many... Thymine? Guanine? Cytosine?
Thymine = 100 Guanine = 900 Cytosine = 900
Pyrimidines of RNA
Cytosine & Uracil
Purines of RNA
Adenine & Guanine
Pentose sugar of RNA
Ribose Sugar
Consists of a single strand of nucleotides that can double back on itself and form a hairpin shape
RNA structure
3’ - TACGTTCCATAG - 5’
mRNa transcript of this DNA template is:
5’ - AUGCAAGGUAUC - 3’
Three types of RNA
- ribosomal RNA (rRNA)
- transfer RNA (tRNA)
- messenger RNA (mRNA)
Coding RNA
messenger RNA (mRNA)
Non-coding RNA
ribosomal RNA & transfer RNA
Prokaryotic DNA is organized in one of two forms:
relaxed circle, or supercoiled DNA
Eukaryotic DNA wraps around these protein molecules to allow it to condense and take on a more closed form
Histones
Nucleosomes
coiled repeating units of DNA wrapped around histones
DNA Replication process
Parental DNA strands open and hydrogen bonds are broken to allow DNA Polymerase to read sequence and form a new daughter strand from the template
DNA Replicas are comprised of
1 Parental strand and 1 New daughter strand
Prokaryotic DNA Synthesis Process
DNA Polymerase Enzymes bind to the Origin of Replication and move away from each other (bidirectional) when they reach the Terminus the new circular chromosome has been created
Eukaryotic DNA Synthesis Process
Sets of DNA Polymerase enzymes bind to multiple origins of replication and move bidirectionally
The molecule of DNA that is read and interpreted to synthesis the new daughter strand is called
DNA template
DNA templates are always read in the _____ direction and synthesized in the _____ direction
3’ - 5’ ; 5’ - 3’
DNA polymerase can’t recognize the DNA template until a short strand of RNA primer is attached to it. This is synthesized by the enzyme_____
Primase
These are polymerized together to form a daughter stand of DNA
Deoxynucleotides
Binds to both sides of DNA at the Replication fork to catalyze synthesis of daughter strands
DNA Polymerase III
The enzyme opens up and breaks the hydrogen bonds between bases at the origin sites
DNA Helicase
Weak spots where Helicase can more easily break bonds
Adenine & Thymine (only 2 hydrogen bonds)
Bind to DNA to prevent reformation of hydrogen bonds until DNA Polymerase III can read and begin replication process
Single-stranded DNA binding proteins (SSBs)
ahead of the replication fork this enzyme unwinds DNA to relieve tension caused by Helicase to prevent “knots”
DNA Gyrase
Leading strand
the strand that is oriented in the 3’ to 5’ orientation
Lagging strand
has to get bent due to the fact that it is in the 5’ to 3’ orientation and is therefore synthesized discontinuously
Fragments formed on the lagging stand due to discontinuous synthesis
Okazaki fragments
works on lagging strand to remove primers and fills DNA gaps with correct nucleotides
DNA Polymerase I
enzyme that creates the covalent bonds to join Okazaki fragments to form a complete strand
DNA ligase
Has the ability to backup one base and remove a mismatched base
DNA polymerase III
DNA replication occurs faster in _____ with a rate of 750 to 1000 base pairs/ second
and slower in _______ at a rte of 50 - 100 base pairs per sec.
faster - prokaryotes
slower - eukaryotes
the process of transcription, translation, & conformation to interpret the DNA code & produce functional protein
Gene Expression
small linear sequence of nucleotides with a fixed start & end point
Gene
a set of three nucleotides that codes for a single amino acid
Codon
T/F All genes code for proteins
False - tRNA & rRNA function as is
T/F One gene produces one polypeptide
True
the orientation in which a set of nucleotides are to be read
Reading Frame
Only one strand of DNA contains the gene. This strand is called the
Template Strand
This strand is interpreted by RNA polymerase to direct and create the RNA molecule (tRNA, mRNA, rRNA)
Template Strand
the complementary strand
Coding Strand
The _______ & the ________ are most important gene regions in the transcription steps.
Promotor; terminator
The ________ & the ________ are most important in directing translation
leader; trailer
