MIDTERM Flashcards
(112 cards)
1
Q
Complex organic compounds found in all living cells
A
NUCLEIC ACIDS
2
Q
TWO KINDS O NUCLEIC ACIDS
A
- DNA- deoxyribonucleic acid
- RNA ribonucleic acid
3
Q
It is found primarily in the nucleus of
cells; hence it is referred to as nuclear
DNA (nDNA).
A
DNA
4
Q
found primarily in the cytoplasm, the part
of the cell surrounding the nucleus.
A
RNA
5
Q
are responsible for the storage and
transmission of genetic information in all living
organisms.
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DNA and RNA
6
Q
is the control and direction of protein synthesis in body
cells.
A
DNA’s major function (RNA is also involved)
7
Q
Are molecules that act as the building
blocks of genetic information in DNA
and RNA.
-Also known as nucleobases
A
Nitrogenous bases
8
Q
are molecules that contain nitrogen atoms
and are crucial for the transmission of
genetic information in living organisms.
A
nucleobases
9
Q
act as the building blocks of genetic
material. They have a ring structure that
is made of carbon and nitrogen atoms.
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Nitrogenous bases
10
Q
it is made up of nitrogenous base which
is attached to a 5 carbon sugar molecule,
along with a phosphate group forming
the backbone of the molecule.
A
Nucleotide
11
Q
There are two categories of nitrogenous
bases that serve as essential
components of nucleotides; these include
A
- Pyrimidine
- Purine
12
Q
is constituted by a six-membered ring made up of carbon and nitrogen atoms. This ring is constituted by four
carbon atoms and two nitrogen atoms in its
structure. In nucleotides, the primary types of
pyrimidines that exist include cytosine,
thymine in DNA.
A
Pyrimidines
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Q
are essential for encoding genetic
information and play a crucial role in protein
synthesis; during transcription, they provide
the template for mRNA formation.
A
Pyrimidines
14
Q
is present in case of thymine, that pairs with adenine with two hydrogen bonds. The base pairing is responsible for the stability of these genetic molecules
A
uracil
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Q
is constituted by a double-ring system i.e. a pyrimidine ring is fused with an imidazole ring.
A
Purine
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Q
contains three carbon atoms and two nitrogen atoms, forming a five membered ring structure.
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purine ring or the
imidazole ring
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Q
the primary types of purines
that exist include adenine and guanine. These
are found in both RNA and DNA.
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nucleotides
18
Q
function as signaling molecules in processes including neurotransmission, and immune response.
A
Purines
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Q
IN DNA, Adenine binds to
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THYMINE
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Q
in RNA, adenine binds to
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URACIL
21
Q
- being a purine base, has a double-ring structure.
- forms complementary bonds with thymine in DNA
and with uracil in RNA via two hydrogen bonds. This complementary bonding of bases is essential for the double helical structure of the DNA and in the process of
transcription in RNA synthesis.
A
Adenine
22
Q
also responsible for the formation of various compounds and derivatives including adenosine monophosphate, adenosine diphosphate, adenosine triphosphate, Sadenosylmethionine and nicotinamide adenine dinucleotide.
A
Adenine
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Q
also a purine, characterized by a double-ring structure.
- pairs with cytosine via three hydrogen bonds in both
DNA and RNA. This complementary base pairing helps in the stabilization of the secondary structure of RNA molecules and the double helical structure of the DNA.
A
Guanine
24
Q
is an essential component of various compounds such as guanosine, guanosine monophosphate,
tetrahydrofuran, guanosine triphosphate, and nicotinamide guanine dinucleotide.
A
Guanine
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is a pyrimidine base, which is formed of a single-ring structure. Cytosine pairs with guanine in both DNA
and RNA. This complementary pairing aids in DNA replication and transcription processes.
Cytosine
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forms compounds and derivatives that have crucial roles in energy metabolism, genetic information transmission, and various biochemical reactions. These compounds and
derivatives include cytidine, cytidine diphosphate, cytidine triphosphate, deoxycytidine, and 5-methylcytosine.
Cytosine
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- is another pyrimidine base, similar to cytosine, having a single-ring structure.
-In DNA, THIS pairs specifically with
adenine via two hydrogen bonds.
- This specific pairing is essential for the accurate replication of DNA during cell division, as the accurate replication ensures that the genetic information is passed correctly to the daughter cells.
Thymine
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is a crucial component of various compounds that help in the process of replication, and repair within cells. These compounds include deoxythymidine, thymidine
monophosphate, thymidine diphosphate, thymidine triphosphate, 5- methyluridine, and thymine glycol
Thymine
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- is a pyrimidine, which has a similar structure to that of thymine but is found in RNA.
-it pairs with adenine via two hydrogen bonds during the process of transcription. This complementary pairing assists in the formation of RNA from a DNA template,
leading to the formation of several types of RNA including mRNA, tRNA, and rRNA.
Uracil
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these derivatives include uridine, uridine monophosphate, uridine diphosphate, uridine triphosphate, 5- methyluridine, and pseudouridine.
Uracil
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The nitrogenous bases may form hydrogen
bonds according to
Complementary Base Pairing
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the basic substance of every body cell including the muscles, blood, skin, nails, hair, hormones and internal organs
Protein Synthesis
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the building blocks of proteins
Amino Acids
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8 amino acids that cannot be synthesized by the body so they must be sourced from the food that people eat
Isoleucine, Leucine, Lysine, Methionine,
Tryptophan,Valine, Phenylalanine, Tyrosine
Essential Amino Acids
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amino acids produced / synthesized by the body
➢ e.g. Serine, Proline, Cystine, Glycine, Glutamic Acid,
Histidine, Alanine and such
Non-essential Amino Acids
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stretches of DNA sequences that are represented in the mature form of RNA, including mRNA and tRNA
Exons
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intervening DNA sequences between exons that will be spliced from the maturing RNA molecule
Introns
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usually consists of multiple exons spliced together
RNA Transcript
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the process of making proteins
Protein Synthesis
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the process by which identical copies of DNA are produced
DNA Replication
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3 consecutive RNA nucleotides
Codons
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3 consecutive nucleotides that bond with the codon to form amino acids
Anti-Codons
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short pieces of single-stranded DNA that are complementary to the target sequence needed to start DNA replication / amplification process
Primers
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the enzyme responsible for the unwinding of the double-helix DNA strand during replication process and the production of a replication fork
DNA Helicase
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the enzyme responsible for splitting the double
helix of DNA
RNA Polymerase
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- enzyme that produce a short piece of RNA strand
called primer
DNA Primase
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acts as the starting point for DNA synthesis
Primer
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the enzyme that remove the primers
Exonuclease
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the enzyme that seals up the sequence of DNA into
two continuous double strands
DNA Ligase
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carries genetic message from the nucleus to the cytoplasm in the form of codons for protein synthesis
mRNA (messenger RNA)
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RNA found in the ribosome that allows interaction of mRNA and tRNA
rRNA (Ribosomal RNA)
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is a small RNA molecule that plays a key role in protein synthesis. Transfer RNA serves as a link (or adaptor)
between the messenger RNA (mRNA) molecule and the growing chain of amino acids that make up a
protein.
Transfer RNA (abbreviated tRNA)
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Form a complicated 3-dimensional structures where
strands can loop back and form intra-strand base pairs.
RNA STRUCTURE
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Differences of RNA to DNA
1. Sugar – ribose
2. One Strand – instead of 2
3. Has Uracil – instead of thymine Base Pair: GC and AU
instead of AT
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3 TYPES OF RNA
1. mRNA (messenger RNA)
2. rRNA (ribosomal RNA)
3. tRNA (transfer RNA)
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template for protein synthesis
- messenger and carrier of genetic information
for protein synthesis from DNA to ribosomes
mRNA (messenger RNA)
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forms an integral part of ribosomes
- bind the mRNA and specific enzyme for protein synthesis
rRNA (ribosomal RNA)
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recognize the specific codons and transport the required amino acid
tRNA (transfer RNA)
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- a theory proposed by Francis Crick
- stated that sequence of nucleotides in DNA determines
the sequence of amino acids in proteins
- flow of the genetic information
CENTRAL DOGMA OF MOLECULAR BIOLOGY
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Major Information Pathways
1. DNA Replication
2. Transcription
3. Translation
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- information is transferred from one DNA molecule to another
* Happens in the synthesis phase prior to the cell
division
DNA Replication
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information is transferred from DNA to
an RNA molecule - Conversion of DNA to mRNA
Transcription
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information is transferred from RNA to a
protein through a code that specifies the amino acid
sequence - mRNA to proteins or amino acids
Translation
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➢ The first step of protein synthesis
➢ The process of creating RNA from DNA
➢ The process occurs in the cell’s nucleus
➢ Copying process or synthesis of complementary strand of
RNA from a DNA template
➢ Copy is mRNA
➢ Happens in cytoplasm for prokaryotes, nucleus for
eukaryotes
➢ Performed by RNA polymerase
➢ Transcription is unidirectional
DNA TRANSCRIPTION
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Ribo-nucleotides can only be added to the 3’ end of a
transcript, thus elongation is in 5’-3’ direction
DNATRANSCRIPTION
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3 Steps of Transcription
1. Initiation
2. Elongation
3. Termination
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RNA polymerase binds to the promoter of a gene
Initiation
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serves to target and orient RNA polymerase
* Once docked at the promoter, RNA polymerase unzips
DNA
Promoter
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Only 1 strand of the DNA is used as a template in creation of mRNA
Elongation
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Triggered by a specific DNA sequence in
the gene called the terminator.
- The transcription process allows the cell to produce shot term copies of genes that can be used as the direct source of information for protein synthesis.
Termination
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DNATRANSCRIPTION
Process:
1. RNA polymerase splits the double helix
2. RNA nucleotides will then match the unpaired DNA strand
3. While the mRNA strand is being created, the DNA strand that previously paired with the RNA nucleotides will start to zip together with the other DNA strand
4. RNA polymerase will detach itself at the end of the final
process
5. The resulting mRNA carries the genetic information copied from DNA in the form of a series of three-base code “words,” each
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- Also called as protein synthesis
- Codons of mRNA are converted into protein
- Involves decoding the language of nucleic acids and converting it into the language of proteins
- Takes place at a ribosome
DNA TRANSLATION
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language of mRNA
Codon
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the set of rules that determine how a nucleotide sequence is converted into the amino acid
sequence of proteins
* Happens in ribosomes in prokaryotes and ER for
eukaryotes
Genetic Code
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Group of 3 nucleotides that coded for particular amino
acid such as
AUG, UAA
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is the start codon in bacteria that codes for formyl methionine rather than methionine (eukaryotes)
* There are 64 codons but only 20 amino acids
AUG
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Type of Codons
1. Sense Codons –
2. Nonsense Codons
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61 including the AUG or the start codon
Sense Codons
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3 stop codons (UAA, UAG, UGA)
Nonsense Codons
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Is made in the cytoplasm in the prokaryotes
and nucleolus in the eukaryotes
Ribosomes (rRNA)
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holds the next codon
A site
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holds the first codon
P site
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holds the deacylated tRNA before it leaves the ribosome
E site
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- To direct the orderly binding of tRNAs to codons
- To assemble the amino acid brought there into a chain producing proteins
Ribosomes
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each has a binding site for an amino acid
tRNA
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- each tRNA is specific for a single amino acid, it must be able to recognize
the codon on the mRNA that codes for that particular amino acid
- has specific three-nucleotide sequence anticodon
- example if the mRNA is UUU, its anticodon is AAA.
true
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- a sequence of three bases complementary to a codon
- matches up with the appropriate mRNA codon like a lock and key
Anticodon
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DNA TRANSLATION Process:
1. The mRNA leaves the nucleus and takes its chemical message to the cytoplasm of the cell.
2. The mRNA attaches / binds with ribosomes and a start codon (usually AUG) is read.
3. Transfer RNA (tRNA) deliver amino acids to the mRNA (the type of amino acid delivered depends on the anti codon carried by the tRNA.
4. The next tRNA molecule moves in and matches with the mRNA codon while the amino acid form peptide bond.
5. The previous tRNA detaches and mRNA moves for the next mRNA molecule to come in.
6. The peptide bond grows longer until a stop codon is reached.
7. A protein is then formed and ready to fold to become
functional.
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- Ribosome assembles at specific AUG of mRNA
- Ribosome binds 2 tRNA-amino acids, 2 codons at a same time; matching complementary anti-codons with mRNA codons
Initiation
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Ribosome catalyzes peptide bond formation between amino acids attached to each Trna
- Ribosome shifts 3 nucleotides (1 codon) on mRNA and repeats the process
Elongation
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Stop codon causes translation to end.
Termination
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are codons within an mRNA molecule that indicate
the start of protein translation.
Start codons
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is the most common start codon and serves as the start
signal for translation initiation.
AUG
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In protein synthesis, AUG codes for the amino acid
methionine
(Met)
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Stop Codons
* Out of the total 64 codons, there are three codons that do not specify or correspond to any amino acids. These codons are known as stop codons.
* Stop codons, also called termination or nonsense codons, serve as signals to terminate the process of protein synthesis during translation.
* The three stop codons are UAA, UAG, and UGA.
* Stop codons were first discovered in 1965 by Sydney Brenner’s experiment on T4 bacteriophage.
* UAG was the first stop codon to be identified. It is also called the amber codon. UGA is called the opal codon, and UAA is called the ochre codon.
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The process by which DNA makes a copy of itself during cell division
* DNA is passed from one cell to another when new cells are formed in mitosis and meiosis.
* When the gametes formed from meiosis unite at fertilization, DNA from each parent is passed onto the offspring.
DNA REPLICATION
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To be able to pass on DNA the original cells cannot lose their DNA. Therefore, the DNA in a cell must be
copied or replicated
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DNA replication occurs during the stage of cell division called
interphase
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DNA does not unzip entirely. It unzips in a small area called
replication fork
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oriented from 3’-5’ (template strand and upper)
Leading Strand
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oriented from 5’ – 3’ (produced strand and lower)
Lagging Strand
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The DNA replication always start in
5
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Bases along the two strands of double helical DNA are
complementary
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The bond between the complementary bases is called as
hydrogen bond
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2H bond
Adenine and Thymine
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3H bond
Guanine and Cytosine
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The lagging strand is discontinuous, these strands are short sequences and called as
Okazaki fragment
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requires the presence of several cellular proteins that direct a particular sequence of events.
DNA replication
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The separation of the two single strands of DNA creates a
‘Y’ shape called a
replication ‘fork’.
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Primers (produced by an enzyme called primase) come
along and bind to the end of the leading strand. The primer
acts as the starting point for DNA synthesis.
* DNA polymerase binds to the leading strand and then
‘walks’ along it, adding new complementary nucleotide
bases (A, C, G and T) to the strand of DNA in the 5’ to 3’
direction.
* This sort of replication is called
continuous
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* Numerous RNA primers are made by the primase
enzyme and bind at various points along the lagging strand.
* Chunks of DNA, called Okazaki fragments, are then
added to the lagging strand also in the 5’ to 3’ direction.
* This type of replication is called
discontinuous
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seals up the sequence of DNA into two continuous double strands.
DNA ligase
