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58 Cards in this Set

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What are the two types of nucleic acids?
(1) DNA: Deoxyribonucleic acid
(2) RNA: Ribonucleic Acid
Where is DNA found?
Found within the cell nucleus

Uses:
- Storage and transfer of genetic information
- Passed from one cell to another during cell division (mitosis)
Where is RNA found?
Occurs in all parts of cells

Uses:
- Primary function is to synthesize proteins
What is chromatin?
A complex tangle of DNA (a polymer of deoxyribonucleic acid), that carries genetic informations and is twisted around proteins (known as histones)
During cell division, what does chromatin organise itself into?
Chromosomes
What are DNA molecules made up of?
Genes
What are genes?
Individual segments of DNA that contain the instructions that direct the synthesis of a single polypeptide
What is a Nucleic acid?
A polymer of nucleotides
What are Nucleotides?
A five-carbon sugar bonded to a cyclic amine base and a phosphate group
What is the sugar present in RNA?
D-ribose
What is the sugar present in DNA?
2-deoxyribose
What does the prefix "2-deoxy-" mean, present in 2-deoxyribose
Means that an oxygen atom is missing from the C2 position of ribose
How many heterocyclic amines are found in nucleic acids?
5
What amine is only present in DNA?
Thymine
What amine is only present in RNA?
Uracil
What is a nucleoside?
A five-carbon sugar bonded to a cyclic amine base; a nucleotide with no phosphate group.
What is used to denote the atoms in the sugar of a nucleoside and nucleotides?
Numbers with primes

*e.g. 5'
How is a nucleotide named?
Nucleotides are named by adding 5'-monophosphate at the end of the name of the nucleoside
What are nucleotides that contain ribose classified as?
ribonucleotides
What are nucleotides that contain 2-deoxy-D-ribose classified as?
deoxyribonucleotides
What are nucleotides made up of?
Nucleic acids
What type of linkage connects DNA and RNA to nucleotides?
phosphate diester linkages between the -OH group of C3' of the sugar ring of one nucleotide and the phosphate group on C5' of the next nucleotide
Where is the free phosphate group located on a nucleotide?
5' carbon (known as the 5' end)
Where is a free -OH group located on a nucleotide?
3' carbon (known as the 3' end)
How is a nucleotide sequence read?
Starting at the 5' end and identifying the bases in order of occurene
In what directions do each strand of the DNA double helix run?
Opposite directions
What bases always make up the base pairs in the double helix?
One pyrimidine base and one purine base
What type of bonds connect the base pairs in DNA?
Hydrogen bonds
What complementary bases are always put together?
A base opposite a T
C base opposite a G
The B form of DNA is the normal right handed form whereas the Z Form is the alternate left-handed form. True or False?
True
Where does DNA replication begin?
Nucleus
What enzyme catalyzes the the partial unwinding of the double helix when DNA replication begins in the nucleus?
Helicases
What occurs in the unravelling of the DNA?
- Unwinding occurs simultaneously in many specific locations known as origins of replication
- The DNA strands separate, exposing the bases
- These branch points, called replication forks, provide a "bubble" into which the replication process can begin
What are replication forks?
Branch points in the unwinding of DNA that provide a "bubble" into which the replication process can begin
What enzyme facilitates the copying of the single-stranded DNA?
DNA polymerase
What is produced during replication of DNA?
2 identical copies of the DNA double helix; one strand is the template and the other is the newly synthesized strand
What are Ribosomal RNAs?
Outside the nucleus but within the cytoplasm of a cell are the ribosomes, small granular organelles where protein synthesis takes place.

Each ribosomes is a complex consisting of about 60% ribosomal RNA (rRNA) and 40% protein
What are transfer RNAs (tRNA)?
Smaller RNAs that deliver amino acids one by one to protein chains growing at ribosomes; each tRNA carries only one amino acid
What are messenger RNAs?
Carry information transcribed from the DNA; formed within the cell nucleus and transported out to the ribosomes, where proteins will be synthesised
Which of the two newly made DNA strands is transcribed during RNA synthesis?
Template strand
What molecule is complementary to the template strand during RNA synthesis (transcription)?
mRNA; makes it an exact RNA-duplicate of the DNA informational strand
What is a codon?
nce of hree ribonucleotides in the messenger RNA chain that codes for a specific amino acid; also a three-nucleotide sequence that is a stop codon and stops translation
What is an exon?
Small sections of DNA that code for a gene
What are introns?
Introns are sections of DNA that do not code for any part of the protein to be synthesised
What does heterogeneous nuclear RNA refer to?
The initial mRNA strand that contains both exons and introns.
Define "Genetic Code"
The sequence of nucleotides, coded in triplets (codons) in mRNA, that determines the sequence of amino acids in protein synthesis
What are the three 'stop' codons?
UAG, UAA and UGA
What is the 'initiation' codon?
AUG (also codes for the amino acid methionine)
What are the three stages of protein synthesis?
(1) Initiation
(2) Elongation
(3) Termination
What is a Point Mutation?
A single base change
What are the 3 types of Point mutations?
(1) Silent
(2) Missense
(3) Nonsense
What is a Frameshift mutation?
The number of inserted or deleted bases is not a multiple of 3, so that all triplets following the mutation are read differently
What are the 2 types of Frameshift mutations?
(1) Insertion
(2) Deletion
What is a Silent Point mutation?
A change that specifies the same amino acid
What is a Missense Point mutation?
A change that specifies a different amino acid
What is a Nonsense Point mutation?
A change that produces a stop codon
What is a Insertion Frameshift mutation?
Addition of one or more bases
What is a Deletion Frameshift?
Loss of one or more bases