Central Dogma of Molecular Genetics

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Questions and Answers

What is the primary role of helicase in DNA replication?

To remove supercoils ahead of the replication fork

To unwind the DNA helix (correct)

To synthesize RNA from the DNA template

To attach nucleotides to the growing DNA strand

Which of the following correctly describes the difference between prokaryotic and eukaryotic DNA replication?

Prokaryotes tend to have one replication bubble, whereas eukaryotes have multiple (correct)

Eukaryotes use fewer polymerases than prokaryotes

Eukaryotes have smaller, circular genomes compared to prokaryotes

Prokaryotes have multiple origins of replication while eukaryotes have one

During which process is RNA synthesized from a DNA template?

Recombination

Translation

Replication

Transcription (correct)

What results from the hydrolysis reaction involving nucleoside triphosphates during DNA synthesis?

Release of energy for the formation of phosphodiester bonds Signup and view all the answers

What is the main function of topoisomerase during DNA replication?

To relieve the strain of supercoiling ahead of the replication fork Signup and view all the answers

What happens when telomeres become too short?

Cells enter a state of senescence. Signup and view all the answers

How does telomerase relate to cancer cells?

It allows cancer cells to keep dividing indefinitely. Signup and view all the answers

What lifestyle factors can accelerate telomere degradation?

Smoking and UV exposure. Signup and view all the answers

What is the 'Hayflick limit' in relation to cell division?

The maximum number of times a cell can divide before dying. Signup and view all the answers

What structure is essential for healthy telomeres?

A looped end. Signup and view all the answers

What is the primary function of RNA primase during DNA replication?

Places RNA primers on template strands Signup and view all the answers

Which enzyme is responsible for filling in gaps in the lagging strand during DNA replication?

DNA polymerase I Signup and view all the answers

What differentiates epigenetic changes from genetic changes?

Epigenetic changes are reversible and do not alter the DNA sequence Signup and view all the answers

What is an epigenome?

All modifications regulating the activity of genes Signup and view all the answers

What role does methylation play in gene expression?

It inhibits transcription by tightly packing DNA Signup and view all the answers

Which enzyme is significant for forming phosphodiester bonds during DNA replication?

DNA ligase Signup and view all the answers

Which of the following accurately describes telomeres?

They prevent coding regions from being lost during replication Signup and view all the answers

What type of enzyme would add biochemical groups such as methyl or acetyl?

Transferase Signup and view all the answers

Study Notes

Central Dogma of Molecular Genetics

DNA replication is the duplication of DNA for cell reproduction
Transcription is the process of copying DNA to RNA
Translation is the process of using RNA to make proteins

DNA Structure and Replication

DNA is a polymer, a polynucleotide
DNA is composed of 6 billion letters (A,T,C,G) in chromosomes
A=T & C=G
Replication of DNA to RNA used for mitosis

Nucleic Acid (DNA/RNA)

DNA and RNA are nucleic acids
DNA is a polymer of deoxyribonucleotides
RNA is a polymer of ribonucleotides
DNA is a polynucleotide
DNA has a structure of a double helix
RNA is a single-stranded molecule

Protein

Proteins are complex molecules composed of amino acids
Amino acids are the building blocks of protein
Proteins can have complex structures : primary, secondary, tertiary, and quaternary structure
Codons are sequences of 3 nucleotides that specify amino acids

Replication vs Transcription-

Replication uses DNA polymerase to create a copy of DNA
Transcription uses RNA polymerase to create RNA from a DNA template
Translation uses ribosomes to translate mRNA into proteins

Energy in Replication

Energy in nucleic acid replication comes from nucleoside triphosphates
Hydrolysis of phosphates provides energy for phosphodiester bond formation

DNA Replication (more detail)

Chromosomes contain DNA, the genetic material
DNA polymerase is essential for DNA replication
Replication occurs at the replication fork, creating a leading and lagging strand
Okazaki fragments are short DNA sequences on the lagging strand
Helicase unwinds the DNA double helix
Topoisomerase smooths out the DNA strand prior to separation
RNA primer is essential for initial DNA synthesis

Enzymes in DNA Replication

Helicase unwinds the double helix
Topoisomerase removes strain ahead of the replication fork
RNA primase synthesizes RNA primers
DNA polymerase III adds nucleotides to the growing DNA strand
DNA polymerase I removes RNA primers and replaces them with DNA
DNA ligase joins Okazaki fragments

Epigenetics

Epigenome is all the modifications to DNA that affect gene expression
Modifications don't change DNA sequence, only how it's expressed
Examples: methylation, histone modification
Epigenetics affects cell differentiation

Epigenetic Mechanisms

Methylation adds chemical group to DNA, either "switching" genes "on" or "off"
Histone modification changes how DNA wraps around histone proteins, affecting gene expression
Non-coding RNAs control gene expression by affecting coding RNA and histones

Telomeres

Telomeres are repetitive sequences at the ends of chromosomes
Telomeres protect coding regions during replication
Telomeres shorten with each cell division
Telomere shortening can lead to cell aging and death
Cancer cells can produce telomerase to stop telomere shortening, contributing to uncontrolled cell division

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Description

Test your knowledge on the central dogma of molecular genetics, including DNA replication, transcription, and translation. Explore the structure of DNA and RNA and understand how proteins are synthesized. This quiz covers essential concepts related to nucleic acids and protein formation.