BIV. Genetic Material: DNA and RNA Flashcards by Arriane Cyrel (MTI)

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

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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
-

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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

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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

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DNA Structure

o Nitrogenous base
o 5-carbon sugar
o Phosphate ester

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Nitrogenous bases:

Purines
Pyrimidines

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Purines:
Pyrimidines:

-Adenine and Guanine
-Cytosine, Uracil (RNA), Thymine

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nitrogen base combined with 5 of nucleic acids

Nucleoside

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Adenosine = Adenine + ribose

Nucleoside

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Example: Adenosine monophosphate = adenine + ribose + PO4

Nucleotide

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nucleoside joined with a phosphate group (Sugar + base)

Nucleotide

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ADENINE

Adenosine
Adenylic Acid

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GUANINE

Guanosine
Guanylic acid

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CYTOSINE

Cytidine
Cytidylic acid

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THYMINE

Thymidine
Thymidykc acid

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URACIL

Uridine
Uridylic acid

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These are proteins conjugated with a nucleic acid (as a DNA) and is the principal constituent of the hereditary material in chromosomes

Nucleoproteins

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They are also found in the cytoplasm (particularly in the ribosomes synthesis)

Nucleoproteins

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Present in all living cells

Nucleoproteins

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Importance of Nucleoproteins - they are closely associated with [?]

chromosomes

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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

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Functions of Nucleoproteins:

Duplication
Storage, expression and transmission of genetic information

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Deoxyribose: Pyrimidine bases

Cytosine and Thymine

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Deoxyribose: Purine bases

Adenine and Guanine

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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

1. DNA helicase

- Joins Okazaki fragments together

2. DNA ligase

- catalyzes the formation of a new phosphodiester linkage between the nuceotide and the growing strand

3. 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