Nucleic Acids (3.1) Flashcards
Define nucleic acids
Genetic material of all organisms that controls cellular activities
State the 2 types of nucleic acids
- DNA
2. RNA
State what both DNA and RNA are composed of
Nucleotides
Describe the role of nucleic acids
Store and transmit hereditary information and instructions for protein synthesis
State whether DNA can self-replicate. True/False
True.
List the 3 major forms of RNA
- Messenger RNA
- Transfer RNA
- Ribosomal RNA
State what process RNA plays a key role in
Plays a major role in protein synthesis
State the monomer of nucleic acids
Nucleotides
State the 3 basic units of nucleotides
- Phosphate group
- Pentose sugar
- Nitrogenous base
State the 5 different nitrogenous bases
- Adenine
- Guanine
- Cytosine
- Thymine (DNA only)
- Uracil (RNA only)
State the 2 major classifications of nitrogenous bases
- Purines
2. Pyrimidines
State all purines
A and G
State all pyrimidines
C and U and T
Describe purines
Two rings
Describe pyrimidines
One ring
State the process by which free nucleotides link together to form strands
Condensation Polymerisation Reaction
State how many molecules the condensation polymerisation reaction originally occurs between. Specify what molecules these are
Two nucleotides
State what forms as a result of the condensation polymerisation reaction with nucleotides
Dinucleotide
Describe the process of condensation polymerisation reaction with nucleotides and reference related molecular structure
Hydroxyl group (OH) on the 3’ carbon atom of one nucleotide joins with the phosphate on the 5’ carbon of the pentose sugar - forms water
State what structure forms as a result of the continual adding of free nucleotides during a condensation polymerisation reaction
Polynucleotide
Outline the type of bonds joining the nucleotides by the sugar-phosphate backbone
Phosphodiester bonds
State what type of molecule both DNA and RNA are
Polynucleotides
Describe the structure of DNA
Double stranded molecule, consisting of two chains of nucleotides twisted into a double helix
State what the sides of the DNA ladder are composed of
Sugar-phosphate backbone
State the term describing the running of the DNA strands in opposite directions to one another
Antiparallel
State what the rungs of the ladder are composed of
Nitrogenous bases of each nucleotide
Describe complementary base pairing of nucleotides
Occurs between the nitrogenous bases forming the double-stranded DNA molecule
A-T and C-G
State the approximate diameter of the DNA double helix
2 nanometers
Describe the structure of RNA
Single stranded molecule
Compare and contrast DNA and RNA molecules
RNA is single stranded, whereas DNA is double stranded DNA has deoxyribose sugar and RNA has a ribose sugar DNA nucleotides (A, T, G, C) and RNA nucleotides (A, U, C, G)
State where uracil is more stable
Single-stranded polynucleotides
State the function of DNA in protein synthesis
Provides instructions for the synthesis of proteins
State the function of RNA in protein synthesis
Translates DNA instructions into proteins that carry out essential functions
State what the order of nucleotides in DNA determines
Products that are synthesised
Describe a gene
Region of DNA that contains the information to produce a protein or a functional RNA molecule
State the region in which mRNA is formed and process which forms it
Nucleus by the process of transcription
Describe the function of mRNA
Carries a copy of the nucleotide sequence of DNA that specifies the amino acid sequence for a particular protein
State where mRNA travels to in its’ mature form
Travels from the nucleus to the cytosol where it binds to ribosomes
State the region in which rRNA is formed
Synthesised in the nucleolus
State what organelle is composed of rRNA and protein
Ribosomes
State the role of ribosomes in the function of mRNA
Sites where the information of the mRNA is translated into a chain of amino acids
Describe the function of tRNA
Transfer amino acids from the cytoplasm to the ribosomes
State how many different types of tRNA molecules exist
61 tRNA molecules
State how many codons represent amino acids
64 codons (3 of which are stop codons)
Outline the 3 places for tRNA to bind to the ribosome
- exit site
- peptidyl site
- aminoacyl site
Describe anticodon
Three nucleotides on a tRNA molecule that join to the codons on mRNA by complementary base pairing during translation
Describe codon
Three nucleotides on a mRNA molecule that code for a particular amino acid (or indicate the beginning or end of a translation)
Describe translation
Process in which the base sequence of a mRNA molecule is used to produce the amino acid sequence of a polypeptide
Describe transcription
Process by which a base sequence in DNA is used to produce a base sequence in RNA
Outline the type of bonds joining the complementary nitrogenous bases of nucleotides
Hydrogen bonds
Describe nucleosides
A nitrogenous base bound to a ribose or deoxyribose pentose sugar
Describe the formation of nucleotides
Phosphoric acid and a nitrogenous base are chemically bonded to a sugar molecules by condensation polymerisation reaction (where water is released)
Compare and contrast DNA polymerase and RNA polymerase
RNA polymerase - catalyses RNA synthesis (transcription)
DNA polymerase - catalyses the formation of DNA polymers (DNA replication)
Describe the sense strand
Coding strand - strand of DNA that has the same nucleotide base sequence as the mRNA strand produced by transcription
Describe the template strand
Strand of DNA/RNA used as a template for building a complementary strand of a precise nucleotide sequence
Describe the lagging strand
DNA strand that is replicated discontinuously in the 5’ to 3’ direction
Describe the leading strand
DNA strand replicated continuously which runs in the 3’ to 5’ direction toward the fork
Describe okazaki fragments
Relatively short fragment of DNA synthesized on the lagging strand during DNA replication.
Describe the replication fork
A Y-shaped region in a chromosome that serves as the growing site for DNA replication.
Describe protein synthesis
Process of creating protein molecules, involving transcription and translation
Describe the direction in which mRNA is read
5’ to 3’ direction
Describe the direction in which tRNA is read
3’ to 5’ direction
State what a three base sequence on mRNA is termed
Codon
State what a three base sequence on tRNA is termed
Anti-codon
CCC and CCA both code for the amino acid Proline. This demonstrates that the genetic code is…
Redundant/Degenerate
The mRNA codon encoding Methionine is AUG. The DNA coding for methionine is…
ATG
The genetic code is universal. This means that:
Codons specify the same amino acids in all species
State the specific structure that signals the 3’ end of a nucleotide
Presence of a hydroxyl group
State why you can only ever add a new nucleotide to a 3’ end of DNA
Because there is a hydroxyl group at the end of the 3’ strand
State to what end of a DNA strand new nucleotides are added to
3’ end
State whether or not the DNA code is ambiguous and/or unambiguous
Unambiguous
State whether or not the DNA code is redunant and/or degenerate
Redundant and degenerate
State how the DNA code is redundant/degenerate
Each codon is specific for only one amino acid but a single amino acid may be coded for by more than one codon
State how the DNA code is unambiguous
One amino acid can be coded by several different codons, but each codon only codes for one amino acid
Describe alternative editing
Method used by cells to create many proteins from one DNA strand
State what is produced during transcription
pre mRNA strand
Describe binary fission
Asexual reproductive method in which a single cell divides into two or more parts that are identical to the parent.
Describe meiosis
Process where a single cell divides twice to produce four cells containing half the original amount of genetic information.
Describe non-disjunction of chromosomes
Pair of homologous chromosomes fails to separate during Anaphase I.
State the 4 structures that are identical in homologous chromosomes
- length
- centromere position
- banding pattern
- gene loci (alleles)
State the stages of meiosis
Interphase P1 M1 A1 T/Cytokinese1 P2 M2 A2 T/Cytokinesis2
Compare and contrast codon and anticodon
Anticodon - tRNA
Codon - mRNA
State in which direction DNA can only be synthesised
5’ to 3’ direction
State in which direction the leading strand is formed
5’ to 3’ direction - towards replication fork
State in which direction the lagging strand is formed
5’ to 3’ direction - away from replication fork