LESSON 2 - PRELIM Flashcards
heredity
Gregor Mendel
flies, linkage
Thomas Hunt Morgan
1928: transformation and mice
Frederick Griffith
1944: DNA as the transforming agent
Oswald Theodore Avery, Colin MacLeod and Maclyn
McCarty
late 40’s-early 50’s: base pairing=AT
CG
Erwin Chargaff
(1952: DNA is not a
protein
Alfred Hershey-Martha Chase
1953: chemical structure of DNA –
secondary structure: double-helix
Watson and Crick
mid 1950’s: DNA Replication details:
semi-conservative replication model
Meselson-Stahl
__________ in 1869
Isolated what he called nuclein from the nuclei of pus
cells
Nuclein was shown to have acidic properties, hence
it became called nucleic acid
Friedrich Miescher
structure in the cell nucleus which is the visible
carrier of genetic information
Chromosomes
portion of a chromosome that controlled a specific
inheritable trait
Genes
carries information which directs the process of
protein synthesis
within the nucleic acids are the codes needed for
transcription and translation of proteins
Nucleic Acids
________ (entire set of genes of an organism) size is based
on number of nucleotide pairs present
Genome
Among eukaryotes, there is no
consistent relationship on the C-value (DNA content of
the genome) and the metabolic, developmental, or
behavioural complexity of the organism
C-value paradox
Within the nucleus, __________are located (as pairs)
chromosomes
___________ are tied together (by protein centromere)
Chromosomes
(Telomeres)
Ends of the chromosome
(genes are specific
portions of chromosome coding for a protein which
functions in various phase)
Within the chromosome are genes
(DNA: double-helix
molecule containing base pair)
In the genes are nucleic acids
Composition of Nucleic Acids
Nucleic Acids (repeating series of nucleotide)
Polymers (polynucleotides)
Parts of Nucleotide
A five-membered ring monosaccharide
A nitrogen-containing cyclic compound (nitrogenous
bases)
A phosphate group
Types of Nucleic Acids
DNA (genetic material – doesn’t function without
RNA)
RNA
Sugars
2-deoxyribose (for DNA)
o 5th carbon – phosphate group
o 3rd – next nucleotide attached
Ribose (for RNA)
o 2nd carbon - oxygen
Nitrogenous Base
Purines (2)
o Contains two-fused N-containing ring
Adenine (A)
Guanine (G)
Pyrimidines (3)
o Has one nitrogen-containing ring
Cytosine (C)
Thymine (T)
Uracil (U)
Sugar + Base =
Nucleoside
Adenine + (deoxy)ribose =
(deoxy)adenosine
Guanine + (deoxy)ribose =
(deoxy)guanosine
Cytosine + (deoxy)ribose =
(deoxy)cytidine
Thymine + deoxyribose =
deoxythymidine
Uracil + ribose
uridine
nucleoside formed after combination of
adenine with ribose
Adenosine
NUCLEOSIDE + Phosphate =
NUCLEOTIDE (Tide labada)
Are the building blocks of nucleic acids
Monomers of the DNA and RNA polymers
Is a 5’-monophoshpate ester of a nucleoside
Are named by adding 5’-monophosphate at the end
of the name of the nucleoside
NUCLEOTIDE
Can add additional phosphate groups to form
diphosphate or triphosphate esters (necessary to
produce energy needed in transcription, translation
and repli)
Nucleotides
Bases Deoxyribonucleosides Deoxyribonucleotides
Adenine (A)
Deoxyadenosine Deoxyadenosine 5’-
Monophosphate
(dAMP)
Bases Deoxyribonucleosides Deoxyribonucleotides
Guanine
(G)
Deoxyguanosine Deoxyguanosine 5’-
Monophosphate
(dGMP)
Bases Deoxyribonucleosides Deoxyribonucleotides
Cytosine
(C)
Deoxycytidine Deoxycytidine 5’-
Monophosphate
(dCMP)
Bases Deoxyribonucleosides Deoxyribonucleotides
Thymine
(T)
Deoxythymidine Deoxythymidine 5’-
Monophosphate
(dTMP)
Bases
Ribonucleosides Ribonucleotides
Adenine (A)
Adenine (A) Adenosine Adenosine 5’-
Monophosphate
(AMP)
Bases
Ribonucleosides Ribonucleotides
Guanine (G)
Guanine (G) Guanosine Guanosine 5’-
Monophosphate
(GMP)
Bases
Ribonucleosides Ribonucleotides
Cytosine (C)
Cytosine (C) Cytidne Cytidine 5’-
Monophosphate
(CMP)
Bases
Ribonucleosides Ribonucleotides
Uracil (U)
Uracil (U) Uridine Uridine 5’-
Monophosphate
(UMP)
the repeating sequence of nucleotides form its
primary structure (forming alternating ribose and
phosphate backbone – providing structural stability)
Primary Structure (from polymerization of monomers)
Based on:
o Chargaff rule
Secondary Structure
Obtained by Rosalind Franklin and Maurice
Wilkins
Diagonal image: helical structure of DNA
X-ray diffraction photographs
A, T, G, and C (complimentary) are present
in equimolar quantities (refers to similarity in
molar concentration in DNA hydrolysis;
equal concentration)
If this 2 molecules are placed together, they
form hydrogen bonds
Similar molar concentration upon DNA
hydrolysis
Chargaff rule
o The 2 (single strand of DNA) polynucleotide
chains run in opposite directions
o One 5’ – OH and one 3’ – OH terminal
o Bases are hydrophobic (non polar, tucked
inside)
o Sugar phosphate backbone is hydrophilic (polar,
exposed to environment)
Double helix
Basic protein to w/c the DNA is coiled around
Higher Structure
Further arrangement of DNA in order to organize
them in the chromosomes
Nucleosome
11 base pairs before helix rotates
A form
10 base pairs before helix rotates
B form
_____ is rarest and is only obtained in experiments
Z form
________ was in
B form (common structure of DNA, followed by A)
X-ray photograph (Franklin and Wilkins) of DNA
3 forms of the helical structure of DNA: _____, _____, _______
A, B, Z
12 base pairs before helix rotates (glycosidic
bonds are anti and syn)
Z form
Single strand nucleic acids
Usually located outside the nucleus (but made inside the
nucleus and transported to cytoplasm to do its function)
The important intermediary player in the central dogma
The only genetic material of viruses (viruses are
classified as non-living things because it only has one
genetic material)
Ribonucleic Acids
Three Types of Ribonucleic Acids
Messenger RNA (mRNA)
Ribosomal RNA (rRNA)
Transfer RNA (tRNA)
Codes for protein
Messenger RNA (mRNA)
Forms the core of the ribosomes
Machinery for making proteins
Ribosomal RNA (rRNA)
Matches code for amino acid on mRNA and position
the right amino acid in place during protein synthesis
Transfers free amino acids to the polypeptide chain
Transfer RNA (tRNA)
RNA with enzymatic properties
Functions in mRNA splicing
Ribozyme
Types of nucleic acid
DNA and RNA
Carry the genetic information from the DNA in the
nucleus directly to the cytoplasm
Messenger RNA (mRNA)
Contains 73 to 93 nucleotides per chain
Can carry a single type of amino acid
Every amino acid have one tRNA carrier
There is at least one different tRNA for each of the
20 amino acids
Transports amino acids to the site of protein
synthesis in the ribosomes
Transfer RNA (tRNA)
Complementary to the codon present on the mRNA
(GCC)
Corresponds to the amino acid alanine
Amino acid is connected to the 3’ end of transfer RNA
Antiocodon: CGG
Structural formula of tRNA:
Yello and Blue
Structural formula of tRNA:
Yellow and Blue
Structural formula of tRNA:
nitrogenous
bases
Yellow
Structural formula of tRNA:
sugar
phosphate backbone
Blue
_________
complementary base pairs of mRNA
3 nitrogenous base pairs present at the end
of tRNA is complementary to the codon
present in mRNA
Each anticodon corresponds to a specific
type of amino acid carried by the tRNA
Anticodon arm
RNA that is complexed with proteins in ribosomes
Main component of ribosome
Complex machinery that is the site of protein
synthesis
Ribosomal RNA (rRNA)
2 subunits
of rRNA
________ catalyzes the peptide bond formation
___________ – binds mRNA and tRNA
1 large and 1 small
_________RNA with enzymatic capabilities
Catalytic RNA – they can catalyse different reactions
or initiate different reactions specifically splicing of
mRNA
Catalyse the splicing of mRNA – refers to the
process of removing unnecessary parts of the
mRNA for it to become more efficient in protein
synthesis
Ribozyme
_______ where mRNA will bind
Small subunit
_______ amino acids will combine in order to
form primary structure of proteins
Large subunit
_______ (unit used to determine the sedimentation
rate of the different molecules or compound
s = Svedberg unit
Coding sequence
Expressed sequence
Portion in the mRNA that codes for a specific amino
acid to make protein
Exons
Most important parts of tRNA
anticodon arm and acceptor arm
________ they can catalyse different reactions
or initiate different reactions specifically splicing of
mRNA
Catalytic RNA
________ refers to the
process of removing unnecessary parts of the
mRNA for it to become more efficient in protein
synthesis
Catalyse the splicing of mRNA
Noncoding sequence
Part in the RNA that has no purpose; do not code for
proteins
Intervening sequence
Where DNA analysis happens
- Identifies specific identity in a person using DNA
(to single out an individual they use introns)
- Because every individual have their own unique
sequence of introns
Introns
Occurs in the nucleus (to protect mRNA)
Information encoded in a DNA molecule is copied
into an mRNA molecule
Transcription
Information encoded in an mRNA molecule is used
to assemble a specific protein
Translation
acts as a “manager” in the process of making
proteins
DNA
Means to produce molecules that have the same base
seuquence
To distribute the DNA of the parent cells to its daughter
calls (cells die eventually – It needs to be passed to code
proteins)
Process that ensures the stability of an organism
Producing two identical replicas of DNA
DNA Replication
cell is metabolically active
G1 Phase
DNA Replication (8 hours for normal
somatic cells: body cells
S Phase
cell growth continues
G2 Phase
where the cell will divide
Mitotic phase
– phosphate is connected
5th carbon
2 H bonds
Adenine and Thymine
3 H bonds
Guanine and Cytosine
DNA Replication Models
Semiconservative Replication
Conservative Replication
Dispersive Replication
DNA Replication would create two molecules
Each of them would be a complex of an old
(parental) and a daughter strand
Newly formed molecules is composed of 1 strand
from parent and 1 strand from daughter.
Semiconservative Replication
DNA Replication process would create a brand new
DNA double helix made of two daughter strands
while the parental chains would stay together
Conservative Replication
Replication process would create two DNA doublechains, each of them with parts of both parent and
daughter molecules
Dispersive Replication
nitrogen weighing 15 amu
N15
nitrogen weighing 14 amu
N14
Meselsohn and Stahl Experiment 2 isotopes used
N15 and N14
Only one replication origin is
needed that is because the
chromosomes of prokaryotes are
simple
Prokaryotes
Multiple replication origins are
needed because the chromosomes
of eukaryotes are way more
complex than prokaryotes
Eukaryotic chromosomes have many
bubbles
-
Prokaryote specifically bacteria contain
extrachromosomal DNA which are called _______.
plasmids
Prokaryote specifically bacteria contain
extrachromosomal DNA
Rolling Circle Replication
There are 2 so called origin of the plasmid replication
Single Stranded Origin and Double Stranded Origin
Present on the separated DNA strand and
while the new DNA is being made for the
separated DNA strand the DNA template is
single stranded thus making it single
stranded
Single Stranded Origin
At this point the DNA is double stranded
before a new DNA strand was made
Double Stranded Origin
Unwinds the DNA double helix
- Helicase will cut the paired DNA strands.
Helicase is the equivalent of the UVR in the
Rolling Circle Replication
Helicase
Prevents supercoiling; relaxes the part of
the DNA that is not yet separated.
Topoisomerase
Breaks one DNA strand
and will connect another
strand to became a very
loose strand in a part of the
DNA.
- Although the DNA strand is
loose and can be coiled
again it will not be
supercoiled unlike before
- Prevents supercoiling in
the DNA strand
TYPE I Topoisomerase
Breaks double strands of
the DNA and pass another
loop over it
- Prevent supercoiling within
2 DNA pairs
TYPE II Topoisomerase
Synthesize short oligonucleotides (primers)
Primase
A.k.a. Processivity clamps allows the
leading strand to be threaded through.
- At the same time makes the process in the
leading strand efficient. This clamp protein
helps keep the replication protein in place.
Clamp Protein (PCNA/Proliferating Cell Nuclear
Antigen for Eukaryote
Joins the assembled nucleotides in order to
from nucleic acids
DNA polymerase
DNA Polymerase enzymatic activity (3)
Polymerase
(2) Exonuclease
Endonuclease
Polymerizing the new DNA
strand by adding
nucleotides
Polymerase
Break the sugar-phosphate
backbone in the end of a
nucleotide strand
- Proof reading capacity of
DNA polymerase.
- Nucleotides removed from
the ends
Exonuclease
Remove nucleotide from
the middle nucleotide
strand
- Internal cuts
Endonuclease
Joins Okazaki fragments in the lagging
strand
Ligase
The end-replication problem
Loss of DNA in each eukaryotic
replication cycle because of primer
overhangs
- The answer to this problem are
Telomeres
Termination
Regions of repetitive DNA close to
the ends and help prevent loss of
genes due to this shortening
- G-C rich
Telomeres
Binds and stabilizes the double -
stranded telomeric DNA
- Helps the overhangs to form
protective loops
Telomeric repeat-binding factor
Enzyme normally present on stem cells
and germ cells which catalyzes the
formation of telomeres
Telomerase
The number of cell division an
organism can make
- Caused by the limited and
consumable presence of telomeres
on somatic cells
Hayflick Limit