2 - Genetics & Learning Exercise Questions Prompt Flashcards
the entire complement of genes on all chromosomes normally found in an organism; the hereditary information
genome
basic building block of nucleic acid;
consists of?
nucleotide
1) 5 carbon sugar
2) Nitrogenous Base
3) Phosphate
two types of 5 carbon sugars in DNA
ribose or deoxyribose
nitrogenous base bound to? comprised of?
the first or 1’ (“one prime”) carbon position;
comprised of:
(a) purine
i. Adenine (A)
ii. Guanine (G)
pyrimidine
i. Thymine (T)
ii. Cytosine (C)
iii. Uracil (U) —- only in RNA
phosphate group of DNA bound to?
fifth (or 5’, five-prime) carbon
Binding of DNA nitrogenous bases?
AT (AU) or GC
Adenine to Thymine (or Uracil)
Guanine to Cytosine
phosphate group bound to ?
5’ Carbon
Nitrogenous Base bound to ?
1’ Carbon
Pentose Sugar
Deoxyribose
paired nucleotides (adenine to thymine and guanine paired to cytosine) attached to deoxyribose
double helix (2 strands)
end with no phoshate bound to the 3’ carbon is?
3’ end
end in which phosphate is bound to only the 5’ carbon
5’ end
two strands that run in opposite direction
antiparallel
example of antiparallel
3’ end of one strand pairs up with the nucleotide of the 5’ end (strands are not identical, but complimentary)
forms where short lengths of double-stranded DNA helix unwind (exposing the separated strands)
replication fork
enzymes that cause unwinding (and rewinding)
they break what?
helicase
DNA gyrase
topoisomerase
they break the hydrogen bonds between bases
binds to DNA and inserts complementary nucleotides
DNA polymerase
If parent strand exposes bases ACGGTA what is the complement?
TGCCAT
nucleotides are always added to the exposed ___ end of the growing strand
3’
strands grow in the direction of _ to _
5’ to 3’
DNA polymerase has extreme accuracy because it
edits for errors
newly growing strand having the 3’ end of the exposed nucleotide “facing forward” or “leading to” the replication fork
“leading” strand
the leading stand is ______ replicated
continuously
the strand having the 5’ end of the exposed nucleotide facing toward the replication fork
“lagging” strand
the lagging strand has __ __ __; (growth method)
replicating short fragments
needed to initiate growth in the absence of a nucleotide having a 3’ binding site
RNA primer
RNA polymerase
provides a 3’ site to bind
RNA primer
provides a 3’ site to bind
RNA primer
needed to initiate growth in the absence of a nucleotide having a 3’ binding site
RNA primer RNA polymerase (synthesizes RNA primer)
facilitates linkage of a nucleotide to both 3’ and 5’ bind sites simultaneously, and inserts a nucleotide to join Replicated to Existing
DNA ligase
DNA Ligase think….
linkage of replicated to existing
lagging strand replicates in a _____ manner
discontinuous
the new double-stranded DNA ___ into a helix as the parental DNA unwinds (exposing itself)
re-winds
the new double-stranded DNA ___ into a helix as the parental DNA unwinds (exposing itself)
re-winds
E. Coli DNA replication speed?
FAST… 1000 nucleotides per second (about one gene per second)
What is semiconservative replication?
entire chromosome copied, each double helix has new strand of DNA to one original parent strand
joins the discontinuous fragments of the lagging strand?
DNA ligase
synthesizes RNA primer
RNA polymerase
Large, SINGLE, stranded molecule of nucleotides— messenger, transfer, & ribosomal (uracil replaces thymine)
Ribonucleic acid (RNA)
RNA is attached to
the sugar, ribose
RNA is attached to
R-ibose
DNA is attached to
D-eoxyribose
carries the genetic code from the DNA to the ribosome
“Messenger RNA” (mRNA)
site of protein synthesis
Ribosome
three nucleotides on the mRNA that specify the amino acid to be placed in a polypeptide
Codon
3 nucleotides = ? codons
1 codon
1 codon = ? amino acids
1 amino acid
Genetic code is also called
triplet code
transports and then transfers the amino acid to the developing peptide chain
“Transfer RNA” (tRNA)
look at image on page 6 of pdf
the site on the tRNA that bonds with the codon on the mRNA
Anticodon
specifies which amino acid will be carried by the tRNA
Anticodon
assists protein synthesis by serving as a “facilitator” for the mRNA and tRNA functions
“Ribosomal RNA” (rRNA)
the transfer of the genetic code on DNA gene into a messenger RNA (mRNA) strand by means of DNA-dependent RNA polymerase
Transcription
allows mRNA to be created
RNA polymerase
allows mRNA to be created
RNA polymerase
Steps of Transcription
1) DNA unwinds (exposes nucleotides)
2) RNA polymerase binds to DNA at promoter site (beginning)
3) Complementary RNA nucleotides are joined together in sequence by the RNA polymerase
beginning site of transcription
promoter site
Complementary RNA nucleotides are joined together by the
RNA polymerase
transcription ends when __ _____ reaches the termination region of the gene, and the new single-stranded mRNA is released (DNA re-winds)
RNA polymerase
The synthesis of a polypeptide at the ribosome (amino acid sequence from mRNA)
translation
Steps of Translation
1) mRNA attaches to ribosome w/ “start” codon in place
2) tRNA w/ complimentary anticodon matches to codon on mRNA (first amino acid in place)
3) As matching occurs (mRNA codons to tRNA anticodons) amino acids are linked together and the tRNA is released
4) polypeptide chain released when reaches “stop” codon
Regulation of Gene expression 6 major players
CIIRRO
Constituitive genes Inducible genes Inducible operon Repressible genes Repressible operon Operon
are constantly expressed (transcribed and translated into functional products)
constitutive genes (60-80% of genes)
genes that can be “turned on”
inducible genes
genes that can be “turned off”
repressible genes
related genes that are regulated as a group/series (e.g. which codes for the enzymes of a single metabolic pathway)
Operon
Operon components (pg 8 of PDF)
Repressor Gene
Promoter site
Operator site
Genes of the Operon
codes for a “repressor” protein which can bind to the “operator” region
Repressor gene
region of the chromosome to which the RNA polymerase binds during transcription
Promoter site
region of the chromosome which controls (either permits or blocks) access of the RNA polymerase to the structural genes of the operon; site to which the repressor protein binds (or fails to bind)
Operator site
adjacent genes of the operon which direct the synthesis of proteins with related functions and which are regulated as a unit
Genes of the Operon
genes are expressed only when certain environmental conditions are present (proper substrate present unblocking operator site)
Inducible Operon
Genes that are expressed EXCEPT when certain environmental conditions are present (presence represses, or slows down metabolism and blocks Operator site
Repressible Operon
changes (substitutions or deletions) in the sequence of DNA bases, thus changing the genetic code
Mutation
types of Mutation
Base Substitution
Frameshift Mutation
a single base is replaced with another, thus changing the codon. may result in an improper amino acid in the protein
base substitution
three consequences from base substitution
Silent - no change (in protein)
Missense - different amino acid (in protein)
Nonsense - RNA polymerase is stopped from reading and causes incomplete, nonfunctional protein
Within in frameshift mutation two characteristics
1) Usually results in missense mutation
2) Usually results in significantly different, nonfunctional, or incomplete protein
causes of base substitution and frameshift mutations
Spontaneous - one in 10 million
Chemical mutagens i.e. nitrous base, base analogs (do not pair properly) (antibiotics)
Radiation - X ray, gamma rays, UV light
Genetic Transfer and Recombination 6 examples or types - RPLCTT
Ret People Like Cooking Turtle Tacos Recombination Plasmid Lysogeny Conjugation Transformation Transduction
gain, loss or substitution of entire gene segments or inversions or transpositions of gene sequences to form new combinations of genes
recombinations
Results in major change or non-functional cell
Source of genes may be DNA from the same or another microbe (or RNA for certain viruses)
Recombination
small, circular, self-replicating piece of DNA In bacteria
Plasmid
separate from normal chromosomal DNA
Genes usually not essential for growth of bacterium
Genes often code for ABX resistance or disease
Genetic Engineering– recombinant plasmid inserted into a new host bacterium
Plasmid - extrachromosomal DNA
Viral Gene may code for antibiotic resistance or disease causing factor
Produces new bacteriophage upon separation from the bacterial DNA
Lysogeny
viral DNA incorporated into bacterial DNA
sex pillus used to transfer DNA from one cell to another
A copy of DNA strand or plasmid is transferred to the recipient cell
Conjugation
Gene fragment is transferred through a sex pillus
results in new characteristics for the recipient cell
Transformation
Donor DNA fragment inserted into recipient DNA; typically donor DNA is “naked” or free DNA following a cell breakdown and release after bacterial death
Results in new characteristics for the recipient cell
Bacteriophage is not functional
Transduction
Virus passes gene to bacterial DNA, but gets stuck accidently in bacterial virus and cannot exit
Nitrogenous Bases
Adenine
Thymine
Guanine
Cytosine
Purine Nitrogenous Bases
Purine Cat Food is ALL GOOD
AG - All Good
Adenine
Guanine
Pyrimidine Nitrogenous Bases
TCU
Thymine
Cytosine
Uracil (only in RNA)
Transduction (trans-stuck-tion)
virus is delivery vehicle carrying bacterial DNA… takes it to bacteria where it gets Stuck
extrachromosomal DNA think
Plasmid
viral DNA incorporated into bacterial DNA
Lysogeny
