Biochem Module 7 Flashcards by Rey Jualo

DNA Replication

Genetic information contained in the DNA is transferred to RNA molecules and then expressed in the structure of synthesized proteins.

The Central Dogma of Molecular Biology

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DNA Replication

process by which DNA is copied with very high fidelity.

DNA Replication

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DNA Replication

involves two replication forks, which move in opposite directions

DNA Replication is bi-directional

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DNA Replication

The leading strand copies continuously
The lagging strand copies in segments (Okazaki fragments)

DNA Replication is semi-discontinuous.

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DNA Replication

DNA in the chromosomes replicates itself every _____ (before mitosis and meiosis I occurs)

cell division

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DNA Replication

an enzyme which separate the DNA strand breaking the H bonds at the replication fork

DNA Helicase

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DNA Replication

replicates DNA using each strand as a template for the newly synthesized strand by adding complementary nucleotides.

DNA polymerase III

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DNA Replication

DNA polymerases have “_________” (exonuclease) activity.

proof reading

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DNA Replication

an enzyme that unknots and uncoils

topoisomerase

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DNA Replication

synthesizes short RNA segments called primers that are starting points for DNA polymerase

DNA primase

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binding to single-stranded DNA

SSB (Single-Stranded DNA binding Proteins)

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DNA Replication

filling the gaps; eliminates primers

DNA Polymerase I

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DNA Replication

Ligates Okazaki fragment to rest of lagging strand; enzyme that catalyzes the formation of the phosphodiester bond between pieces of DNA.

DNA Ligase

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DNA Replication

______ is synthesized as a single strand from the point of origin toward the opening replication fork

Leading strand

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DNA Replication

is synthesized discontinuously against overall direction of replication

Lagging Strand

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DNA Replication

series of short segments on the lagging strand

Okazaki fragments

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DNA Replication

Must be joined together by an enzyme

DNA Ligase

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DNA Replication

Replication of the leading strand occurs ______in the _____ direction of the new strand.

continuously; 5’ → 3’

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DNA Replication

Replication of the lagging strand occurs _______. Short DNA fragments are initially synthesized and then ligated together.

discontinuously

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Transcription

process by which the DNA genetic code is read and transferred to messenger RNA (mRNA). This is an intermediate step in protein expression.

Transcription

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Transcription

Only one of the DNA strands is copied

coding or antisense strand

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replicates the DNA sequence into a complementary sequence of mRNA (template or sense strand).

RNA Polymerase

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He isolated nuclein from the nuclei of pus cells

Friedrich Miescher

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Nuclein was shown to have
acidic properties, hence it was called ____?

nucleic acid

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Nucleic acid was previously known as?

Nuclein

Two types of nucleic acids

1. Deoxyribonucleic acid (DNA) 2. Ribonucleic acid (RNA)

carrier of genetic information

DNA

an intermediate in the expression of genetic information and other diverse roles

RNA

The amino acid sequence of a polypeptide is programmed by a unit of inheritance called ____?

gene

# True or False Nucleic acids are **polynucleotides**

True

Building blocks of nucleic acids

nucleotides

linkage between the sugar and organic base residues

N-glycosidic bond

linkage between the sugar and phosphate residues

Phosphoester bond

Nucleotides structure

1. pentose sugar 2. nitrogenous bases 3. phosphate group

What is the difference between Deoxyribose and Ribose in terms of structure, sugar, and nitrogenous base

DNA structure: * double helix * Carbon 2 does not have oxygen (H) * A=T ; C=G RNA structure: * single strand * Carbon 2 has oxygen (OH) * A=U ; C=G

What are the 2 types of nitrogenous bases

1. pyrimidines (C, T, & U) 2. purines (A & G)

have six-membered ring

Pyrimidines

* have a six-membered ring fused to a five-membered ring * Both present in DNA and RNA

Purines

pyrimidines attach to the pentose via the ____ position while purines attach through the ____ position

N-1 ; N-9

Energy currency in cellular metabolism

ATP

Derived from phosphoric acid, H3PO4, at physiological pH exists in the ionic form.

PHOSPHATE GROUP

A portion of a nucleotide without the phosphate group

Nucleoside

nucleoside = ?

nitrogenous base + sugar

# True or False The stereochemistry of the glycosidic bond found in nucleic acids is β

True

Nucleotide = ?

phosphate + sugar + nitrogenous base

2 to 10 nucleotide residues

Oligonucleotides

more than 10 nucleotide residues

Polynucleotides

Sigma factors recognize two highly conserved regions of the promoter.

Transcription: Initiation

Nitrogenous bases are attached to the?

1st carbon

Refers to the helix formed by the interaction of two DNA strands

Secondary Structure of DNA

Tertiary Structure of DNA: ____

Supercoils

# Transcription: Initiation two regions within promoters that are highly conserved:

* Pribnow box * −35 region

# Transcription: Initiation Stretched of 6 nucleotide (TATAAT) located 10 bases before the start of transcription (−10 region)

Pribnow box

# Transcription: Initiation located ~35 bases upstream of transcription

-35 region

* the promoter region has been recognized by the holoenzyme * RNA polymerase begins to synthesize the transcript of the DNA sequence, with the release of the sigma factor.

Transcription: Elongation

does not require a primer

RNA polymerase

(ahead of the transcription site) – relaxed by gyrase

+supercoil

(behind) – relaxed by topoisomerase

-supercoil

* RNA polymerase encounter a stop signal or transcription terminator (e.g. rho protein in prokaryotes; C-G rich hairpin loop) * the RNA polymerase dissociate from the DNA template * the RNA transcript is released.

Transcription: Termination

are sections that code for proteins, and are spliced together with spliceosomes

Exons

which do not code for proteins

Introns

The process by which the genetic code is converted to a protein, the end product of gene expression

Translation

A change in the nucleotide sequence of DNA altering the sequence of amino acids which will affect the structure and function of a protein in a cell.

Mutation

types of mutation

1. BASE SUBSTITUTION “POINT MUTATION” 2. BASE DELETION OR INSERTION

# BASE SUBSTITUTION “POINT MUTATION” The codon containing the changed base codes for the same amino acid

Silent Mutation

# BASE SUBSTITUTION “POINT MUTATION” The change results in a new different amino acid

Missense

# BASE SUBSTITUTION “POINT MUTATION” The change leads to premature termination if the codon containing the changed base become a termination codon.

Non-Sense Mutation

# BASE DELETION OR INSERTION Insertion or deletion of one or two bases will alter the reading frame and this cause extensive change in the translated protein.

Frame Shift Mutation

# BASE DELETION OR INSERTION This lead to the addition of new amino acids (if three bases were inserted), or to the deletion of one amino acid (if three bases were deleted).

Insertion or deletion of one codon or “3 nucleotides”

# True or False Each cell contains about 2 meters of DNA

True

Arises from supercoiling that involves double helices being twisted into tighter, more compact shapes

Tertiary Structure of DNA

DNA is “packaged” by coiling around a core of proteins known as?

histones

rich in lysine and arginine residues

histones

DNA-histone assembly

nucleosome

Types of RNA

1. Messenger RNA (mRNA) 2. Ribosomal RNA(rRNA) 3. Transfer RNA (tRNA)

carrier of genetic information from the DNA in the cell nucleus to the site of protein synthesis in the cytoplasm

mRNA

# True or False mRNA directs amino acid sequence of proteins and is complementary copy of the gene

True

# True or False mRNA has a short lifetime and Has the codon (three bases) for an amino acid in a protein

True

mRNA is also known as?

The starting point of translation

* forms ribosomes by reacting with proteins * accounts for 80-85% of the total RNA of the cell

rRNA

* Transfers amino acids to the site of protein synthesis * Has the anticodon

tRNA

# True or False tRNA is the **largest** of the nucleic acids

False | tRNA is the **smallest**