Unit 8 Flashcards
Nucleic acids are
polymers of nucleotides
has its own unique sequence of bases known as its primary structure.
nucleic acids
what makes up nucleic acids primary structure
bases
They are large molecules in the cell nucleus storing information and direct activities for cellular growth and reproduction
nucleotides
A nucleotide is composed of a
base, a sugar, and a phosphate group
(bond between PO4 and sugar)
phosphodiester linkages
When nucleotides are joined by phosphodiester linkages, (bond between PO4 and sugar)
polynucleotides are formed
2 most important nucleic acids are
DNA (deoxyribonucleic acid) & RNA (ribonucleic acid).
Is DNA or RNA larger
DNA
is the inherited genetic material controlling protein synthesis.
DNA
DNA structure
It is a double helical structure, where the helix is made up of sugar-phosphate groups.
The double helix consisted of
2 polynucleotide strands winding about each other like a spiral staircase.
are seen within the structure which are H bonds between bases
Bridges
The H bond formed is between
the bases, adenine & thymine (2 H bonds) and guanine & cytosine
(3 H bonds) The pairs AT and GC are called
complimentary base pairs
Bases used in DNA are both
purine (adenine & guanine) and pyrimidine (cytosine & thymine)
Sugar used in DNA is a
pentose, deoxyribose.
RNA Structure
The structure is with single chain instead of a double helix as in DNA.
The sugar used in RNA is another
pentose, ribose.
RNA The base pairs are
adenine & uracil and guanine & cytosine.
Alterations in the DNA base sequence leads to
gene mutation.
Small living particles, with 3 to 200 genes, that cannot replicate without a host cell are called
Viruses.
DNA replication takes place in the
nucleus
begins with the “unzipping” of the parent molecule as the H bonds between the base pairs are broken.
DNA replication
Replication takes place from
5 primer (5’) to 3 primer
(3’) Helicase is
the enzyme that splits the two strands.
When a cell divides, each of its double strands of DNA
DNA splits into two single strands
The enzyme, primase produces
short complementary RNA fragments called primers
DNA polymerase
catalyze the replication at open DNA sections termed, replication forks.
what are DNA polymerase
an enzyme
Each of these single strands acts as a template for a new strand of complementary DNA
replication forks
Leading strand
one of the new strand is synthesized continuously and lagging strand is synthesized discontinuously in short, separate segments called Okazaki fragments.
DNA ligase
connects the Okazaki fragments by phosphodiester linkages, leading to the formation of a new lagging strand which matches the leading DNA strand.
end product of DNA replication
2 identical copies of DNA
There are 3 major types of RNA in the cells
mRNA, rRNA and tRNA.
• Messenger RNA (mRNA)
carries genetic information from DNA to ribosomes. DNA is situated within the nucleus while ribosomes appear outside the nucleus.
• Ribosomal RNA (rRNA)
when combined with proteins yield ribosomes, which is the protein synthesis site. It is the most abundant type of RNA.
• Transfer RNA (tRNA)
get specific amino acids to the ribosome for protein synthesis. This RNA interprets the genetic information in mRNA into the amino acid sequence. Each tRNA contains an anticodon, which is a series of 3 bases that complements 3 bases on mRNA. Codon is the set of 3 nitrogen bases representing an amino acid.
Transcription takes place in the
nucleus and then moves onto the cytoplasm
It is the process by which DNA is copied to mRNA, which carries the information needed for protein synthesis.
transcription
Partial unwinding of the double helix must occur before _______ can take place
transcription
Partial unwinding of the double helix is catalyzed by the
enzyme, RNA polymerase
how many strands are transcribed in transcription, while both strands of DNA are copied in replication.
one
Transcription takes place in how many steps
two
end product of transcription
strand of mRNA
DNA template strand —–>
pre-messenger RNA —-> mature RNA
The process takes place within the cytoplasm
DNA translation
how many steps in translation
. It involves 3 steps- initiation, chain elongation and termination. tRNA molecules convert the information in mRNA into amino acids by a process called translation. mRNA binds to ribosomes and each tRNA gets attached to specific amino acids according to their anticodons
Protein synthesis starts when
mRNA binds to a ribosome.
The first codon in an mRNA is called a
start codon
start codon forms
h bonds with methionine
A peptide bond is formed between
C terminus of methionine and N terminus of second amino acid.
Successive tRNAs
bind to and detach from ribosome as they add an amino acid to the polypeptide.
Stop codons release
the polypeptide chain from ribosome, indicating the termination of polypeptide synthesis.
tRNA has 2 major parts which
play an important role in the the process of translation. One is the acceptor stem, where the amino acid is attached. As a result an ester bond is formed between COOH of amino acid and OH of acceptor stem. Another important section is the anticodon area, which is a set of 3 complimentary bases.
Codon is the
set 3 bases in mRNA.
Anticodon is
its complimentary set, found in tRNA.
• Initiation:
Start codon forms H bond with tRNA
• Elongation:
ribosome moves along mRNA from codon to codon, so that tRNAs can attach new amino acids to growing polypeptide chain
• Termination
ribosome meets a codon which has no corresponding tRNAs. Stop codon releases polypeptide chain.
end product of DNA translation
a polypeptide chain of amino acids.
Genetic code consists of
a series of codons in mRNA that specifies the order for protein synthesis.
It is the sequence of nucleotides that determines the sequence of amino acids
genetic code
An amino acid can have how many codons
several
The human Genome Project, completed in 2003, showed that our DNA is composed of
3 billion bases and 21,000 genes coding for proteins
This represents only 3% of the total DNA.
human genome project
Differentiate between nucleic acid and nucleotides
Nucleic acids are polymers of nucleotides, which has its own unique sequence of bases known as its primary structure
What are the components of a nucleotide?
A nucleotide is composed of a base, a sugar, and a phosphate group.
Explain the structure of DNA and RNA
DNA structure: It is a double helical structure, where the helix is made up of sugar-phosphate groups. The double helix consisted of 2 polynucleotide strands winding about each other like a spiral staircase.
RNA structure: The structure is with single chain instead of a double helix as in DNA.
Identify the following as a nucleoside or a nucleotide. Adenosine
nucleoside
Identify the following as a nucleoside or a nucleotide. Cytidine monophosphate
nucleotide
Identify the following as a nucleoside or a nucleotide. Uridine monophosphate
nucleotide
Identify the following as a nucleoside or a nucleotide. Deoxythymidine
nucleotide
Identify the following as a nucleoside or a nucleotide. Guanosine
nucleotide
Differentiate between the base pairs in DNA and RNA.
DNA- adenine & thymine (2 H bonds) and guanine & cytosine.
Which are the 3 major steps in the synthesis of protein?
1) initiation
2) elongation
3) termination
Mention the enzymes involved in DNA replication process. Explain their functions.
Helicase is the enzyme that splits the two strands. When a cell divides, each of its double strands of DNA splits into two single strands. The enzyme, primase produces short complementary RNA fragments called primers. The enzyme, DNA polymerase catalyze the replication at open DNA sections termed, replication forks.
What are the functions of 3 major types of RNA in the cells?
1) Messenger RNA (mRNA) carries genetic information from DNA to ribosomes. DNA is situated within the nucleus while ribosomes appear outside the nucleus.
2) Ribosomal RNA (rRNA) when combined with proteins yield ribosomes, which is the protein synthesis site. It is the most abundant type of RNA.
3) Transfer RNA (tRNA) get specific amino acids to the ribosome for protein synthesis. This RNA interprets the genetic information in mRNA into the amino acid sequence. Each tRNA contains an anticodon, which is a series of 3 bases that complements 3 bases on mRNA. Codon is the set of 3 nitrogen bases representing an amino acid.
What is an anticodon and acceptor stem? Where are they located?
anticodon, which is a series of 3 bases that complements 3 bases on mRNA. Codon is the set of 3 nitrogen bases representing an amino acid. One is the acceptor stem, where the amino acid is attached. As a result an ester bond is formed between COOH of amino acid and OH of acceptor stem.
Name the enzyme that catalyzes transcription
RNA polymerase
Define transcription
It is the process by which DNA is copied (transcribed) to mRNA, which carries the information needed for protein synthesis.
Which are the 3 steps involved in translation?
1) Initiation: Start codon forms H bond with tRNA.
2) Elongation: ribosome moves along mRNA from codon to codon, so that tRNAs can attach new amino acids to growing polypeptide chain.
3) Termination: ribosome meets a codon which has no corresponding tRNAs. Stop codon releases polypeptide chain.
What is the final product of:
Replication
Transcription
Translation
a) Replication End product: 2 identical copies of DNA b) Transcription End product: a strand of mRNA. c) Translation End product: a polypeptide chain of amino acids.
Define genetic code.
the nucleotide triplets of DNA and RNA molecules that carry genetic information in living cells.
Differentiate between codon and anticodon.
• Each tRNA contains an anticodon, which is a series of 3 bases that complements 3 bases on mRNA. Codon is the set of 3 nitrogen bases representing an amino acid.
The process of making RNA from DNA is called
The process by which DNA is copied to RNA is called transcription.
The process of assembling a protein from RNA is called
that by which RNA is used to produce proteins is called translation.
How many amino acids are attached to a single tRNA?
In the genetic code, codons made of of three bases specify an amino acid.
How many bases are in a codon? In an anticodon?
Three
Three
How many bases are found in DNA? RNA?
4
Which base is found in RNA but not in DNA?
Uracil
consists of a nitrogen containing a base and a sugar
nucleoside
which of the following is found in RNA but not DNA
Uracil
Guanine is one example of a nitrogen base that is a
pyrimidine
The bonds that link the base pairs in the DNA double helix are
hydrogen
when DNA replicates a guanine forms a base pair with
cytosine
the two new DNA helix formed in replication
contain one daughter and one parent strand
what is the process in which the DNA double helix unfolds and each strand serves as a template for the synthesis of a new strand?
replication
which of the following types of RNA carries the genetic information from DNA in the nucleus to the cytoplasm for protein synthesis
mRNA
what is the section of mRNA produced from the DNA template?
3’ AAGCGAA 5’
5’ UUCGCUU 3’
when mRNA is synthesized using the information from DNA the process is called
transcription
codons are base pair sequences that
code for amino acid
the codon is found on ___ and the anticodon is found on ____
mRNA, tRNA
which of the following is not a step in translation
unwinding of two strands of mRNA
the enzyme which splits double strand of DNA
helicase
set of 3 nitrogen bases representing an amino acid
codon
end product of DNA transcription
single strand of mRNA
true/false
the anticodon sequence is found in mRNA
false
t/f
messenger RNA carries protein synthesis information from nucleus to ribosomes
true
T/F?
okazaki fragments are short segments formed by DNA polymerase in the daughter DNA strand
True
T/F the backbone of a nucleic acid is the nitrogen bases
false
t/f? a nucleotide consists of only a base and a sugar
false
which of the following can be found in DNA
deoxyadenosine
the nucleotides in the backbone of DNA are held together by ___ bonds
phosphodiester
which one of the following base pairs is found in DNA
adenine thymine
acceptor stem is found in
tRNA
the enzyme that connects okazaki fragments by phosphodiester linkages
DNA ligase
type of RNA that carries genettic information from DNA to ribosomes
rRNA
the end product of DNA translation
polypeptide chain
sugar used in RNA
ribose
translation is the process whereby
protien is synthesized from mRNA
anticodon of UAG is
AUC
which of the following is not a step in protein synthesis
unwinding of two strands of mRNA
start codon is
tRNA
