BIV. Genetic Material: DNA and RNA Flashcards
The unit structure of all living things is the [?]. Suspended in the nuclei of cells are [?], which consist largely of proteins and nucleic acids.
cell
chromosomes
A simple protein bonded to a nucleic acid is called a [?]. Nucleic acids are polymers of nucleotides and contains either the sugar [?] the sugar [?]. Accordingly, they are called deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) respectively.
- nucleoprotein
- -
Macromolecules which were first discovered in the nuclei of cells, which contain all the information to direct the activities of a cell and its reproduction
Nucleic acids
o Knowledge of the structure and function of [?] is essential in understanding genetics and many aspects of disease, pathophysiology, as well as the genetic basis of the disease
nucleic acid
DNA Structure
o Nitrogenous base
o 5-carbon sugar
o Phosphate ester
Nitrogenous bases:
- Purines
- Pyrimidines
- Purines:
- Pyrimidines:
-Adenine and Guanine
-Cytosine, Uracil (RNA), Thymine
nitrogen base combined with 5 of nucleic acids
Nucleoside
Adenosine = Adenine + ribose
Nucleoside
Example: Adenosine monophosphate = adenine + ribose + PO4
Nucleotide
nucleoside joined with a phosphate group (Sugar + base)
Nucleotide
ADENINE
Adenosine
Adenylic Acid
GUANINE
Guanosine
Guanylic acid
CYTOSINE
Cytidine
Cytidylic acid
THYMINE
Thymidine
Thymidykc acid
URACIL
Uridine
Uridylic acid
These are proteins conjugated with a nucleic acid (as a DNA) and is the principal constituent of the hereditary material in chromosomes
Nucleoproteins
They are also found in the cytoplasm (particularly in the ribosomes synthesis)
Nucleoproteins
Present in all living cells
Nucleoproteins
Importance of Nucleoproteins - they are closely associated with [?]
chromosomes
Properties of Nucleoproteins:
[?]
Soluble in [?] with which they form salts.
Precipitated from solutions by [?] but are redissolved by dilute HCl
Not coagulated by [?]
Exhibit similar precipitation and color reactions with [?]
Acidic
alkalies
acetic acid
heat
proteins
Functions of Nucleoproteins:
- Duplication
- Storage, expression and transmission of genetic information
Deoxyribose: Pyrimidine bases
Cytosine and Thymine
Deoxyribose: Purine bases
Adenine and Guanine
Deoxyribose: Phosphate group
Present
Deoxyribose: Location
Nucleus, mitochondria, bacteria, viruses
Deoxyribose: Structure
Linear or circular
Deoxyribose: Feulgen’s test
Red
Deoxyribose: Dische test
Blue
Deoxyribose: Aniline
Red
Deoxyribose: Orcinol test
Negative
Ribose: Pyrimidine bases
Cytosine and Uracil
Ribose: Purine bases
Adenine and Guanine
Ribose: Phosphate group
Present
Ribose: Location
Cytoplasm, ribosomes, Nucleolus, bacteria, viruses
Ribose: Structure
Branched
Ribose: Feulgen’s test
Negative
Ribose: Dische test
Negative
Ribose: Aniline
Negative
Ribose: Orcinol test
Green
Nucleic acid composition:
Sugar (pentose)
Phosphate (from phosphoric acid)
Nitrogenous base (Purine and Pyrimidine)
− A 5carbon sugar (ribose or deoxyribose)
Sugar (pentose)
− Green Has a very acidic property which gives nucleic acids their acidity
Phosphate (from phosphoric acid)
Nitrogenous base
(Purine and Pyrimidine)
o DNA is a polymeric substance made up of four nucleotides (A, G, C, T).
Deoxyribonucleic acid (DNA)
o The size of the [?] varies with the complexity of the organism; more complex organisms tend to have larger DNAs – for example, simple bacteria like Ohave about 8 million nucleotides in their DNA, while human DNA contains up to 500 million nucleotides
DNA polymer
is the predominant conformation (twisted ladder structure) of DNA
o Double helix
o The 2 strands of the DNA structure is [?] - each has an opposite polarity to the other
Anti parallel
o The [?] component of the DNA is located on the side of the ladder
sugar-PO4
Deoxyribonucleic acid (DNA)
o Nitrogenous bases are connected by [?] (located on the steps of the ladder)
H bonds
The 2 strands are held together by
Complementary base pairing
• A = T (DNA)
• A = U (RNA)
• G = C
Complementary base pairing
There are always the same number of A bases and T bases and G as C
Complementary base pairing
o The base composition of the DNA of all organisms is CONSTANT
DNA: Chargaff’s rule
o The amount of purine bases is always equal to the amount of pyrimidine bases (1:1 ratio)
DNA: Chargaff’s rule
o The structure of DNA, according to Watson and Crick, consists of two polymeric strands of nucleotides in the form of a (?) with both nucleotide strands coiled around the same axis.
double helix
o Along each strand are alternate [?] and [?], with one of the four bases – adenine, guanine, cytosine, or thymine attached to deoxyribose as a side group
phosphate
deoxyribose units
is held together by hydrogen bonds extending from the base on one strand of the double helix to a complementary base on the other strand.
double helix
o The four bases are [?] in their ring structures.
flat
o The structure of the [?] has been likened to a ladder that is twisted into a double helix, with the rungs of the ladder kept perpendicular to the twisted railings
DNA
o The [?] and [?] alternate along the two railings of the ladder, and two nitrogen bases form each rung of the ladder
phosphate and deoxyribose units
o Stores all the information about the proteins that make-up the organism
DNA: genetic material
o (?) DNA segment that codes for the biosynthesis of specific protein
Gene
is the biochemical process by which DNA molecules produce exact duplicates of themselves
o DNA replication
o Each time the cell divides, an exact copy of the DNA of the parent cell is needed for the new daughter cell
o DNA replication
- causes the DNA helix to unwind
- DNA helicase
- Joins Okazaki fragments together
- DNA ligase
- catalyzes the formation of a new phosphodiester linkage between the nuceotide and the growing strand
- DNA polymerase
– short segments of the DNA molecule
▪ Okazaki fragments
− The enzyme HELICASE causes the two strands to unwind, producing two separate strands
o Step 1
− Free nucleotides pair with their complementary base on the template strands by means of hydrogen bonds
o Step 2
− DNA polymerase joins the newly attached nucleotides to create one continuous strand in the 5’ to 3’ direction
o Step 3
− The other strand is formed in short segments (Okazaki fragments) in the 3’ to 5’ direction. The segments are joined together by DNA ligase
o Step 4
− Single-stranded
Ribonucleic acid (RNA)
: serves as the backbone of its structure
− Ribose-PO4
− Nitrogenous bases are variable and stick out from the backbone
Ribonucleic acid (RNA
− Ratio is NOT always 1:1 (does not follow the Chargaff’s rule)
Ribonucleic acid (RNA
Ribonucleic acid (RNA
– instead of thymine
Uracil
Ribonucleic acid (RNA)
− Sugar :
ribose
− Can have a secondary structure:
hairpins, step-loop structure
Note: are classified according to their structure and function
RNA molecules
is the sugar unit in RNA
Ribose
is replaced by uracil in RNA.
Thymine
is single stranded, thus it does not contain equal amounts of specific bases
UracilRNA
The RNA is much [?] than the DNA (from 75
smaller
RNA: Functions
Serves as the [?] of genetic information to the site of protein synthesis (mRNA)
Essential component of the [?]
Serves as the genetic material for some [?]
carrier
ribosomes
viruses
Messenger RNA
Amount:
No. of nucleotides:
15%
1200
Transfer/Soluble RNA
Amount:
No. of nucleotides:
5%
75
Ribosomal RNA
Amount:
No. of nucleotides:
80%
1800
– carries the genetic code to the cytoplasm for the formation of protein
mRNA
transfers the amino acid molecules to the ribosomes during protein synthesis
tRNA
constitute 40-50% of the ribosomes (attached to the ER for protein synthesis);
rRNA
Function is structural and may also be catalytic for some translation reactions
rRNA
Three Stages of Protein Synthesis:
Transcription
Translation
Formation of Polypeptide chain
Describes the flow of genetic information from DNA to RNA to Proteins
The Central Dogma of Molecular Biology
DNA Replication → Transcription → Translation
The Central Dogma of Molecular Biology
: groups of 3 adjacent bases that specify an amino acid
▪ Codons/Coding triplet
▪ Most amino acids are coded for by
more than one codon
: stop/termination codons (code for the termination of translation)
▪ UAA, UAG, UGA
▪ The [?] are more significant and important.
first 2 bases
▪ The [?] is variable and sensitive to mutation
3rd base
= start codon
▪ AUG
: stop/termination codons (code for the termination of translation)
UAA, UAG, UGA
The [?] are more significant and important
first 2 bases
2 Types of Nucleoproteins
- Histones
- Protamine
: major protein that condenses the sperm; replaces histones
- Protamine
: weak bond
- Phosphodiester bond
: between nitrogenous bases
- Hydrogen bond
: synthesize from 5’ to 3’ or few strands of RNA
- PRIMASE
: towards replication fork
- LEADING STRAND
: away replication fork
- LAGGING STRAND
