60 Questions
Which molecule makes up the sides of a DNA molecule?
Phosphate group
How many deoxyribonucleotides make up DNA?
4
What are the major and minor grooves of DNA?
Structural features that allow DNA binding proteins to attach
Which enzyme unwinds the DNA double helix during replication?
Helicase
What is the first step that must occur in DNA replication?
Unwinding the DNA double helix
What does DNA stand for?
Deoxyribonucleic acid
How many base pairs are in a full turn or twist of a DNA molecule?
10.5
Which enzyme relieves the buildup of torque while unwinding the DNA double helix?
Gyrase/Topoisomerase
Which enzyme replaces RNA primers with DNA during DNA replication?
DNA polymerase I
What are the building blocks of DNA?
Deoxyribose, nitrogenous base, and a phosphate group
Which type of modification involves the addition of a phosphate group to a protein?
Phosphorylation
Which amino acid residues are involved in modification?
Lysine, Serine, and Arginine
What is the 'histone code' hypothesis?
A hypothesis about the role of histones in chromatin structure and gene expression regulation
What is epigenetic inheritance?
Inheritance of changes in chromatin structure and gene expression
Do prokaryotes have histones?
No, prokaryotes do not have histones
How many types of histones are there in eukaryotes?
5
What is the function of telomerase?
It elongates telomere sequences in DNA
What are LINES and SINES?
Transposable elements
What is the most abundant repetitive element in the human genome?
Alu elements
What is the function of a chromatin remodeling complex?
It alters the position of nucleosomes along DNA
Which enzyme uses the energy of ATP hydrolysis to separate the two strands of DNA during replication?
DNA helicase
What is the function of DNA polymerase in DNA replication?
Adding nucleotides to the growing strand of DNA
How many DNA polymerases are found in E. coli?
3
What are the functions of topoisomerases?
Relieving tension in DNA
What is the role of a single strand DNA-binding protein in DNA replication?
Preventing base pairs from re-forming
What is the average length of Okazaki fragments in prokaryotes?
100-200 nucleotides
In which direction is DNA synthesis always synthesized?
5'à3'
What is the function of Primase in DNA replication?
Producing an RNA primer for DNA synthesis
What is the proofreading function of DNA polymerase?
Checking each nucleotide during DNA synthesis
What are the differences and similarities of DNA replication in eukaryotes and prokaryotes?
They have different directions of DNA synthesis
Which enzyme is responsible for unwinding the DNA double helix during replication?
Helicase
What is the function of DNA polymerase III in DNA replication?
Synthesizes new DNA strands
What is the function of DNA polymerase I in DNA replication?
Replaces RNA primers with DNA
Which enzyme relieves the buildup of torque while unwinding the DNA double helix?
Gyrase
What are the major and minor grooves of DNA?
Depressions formed by the sugar-phosphate backbones
What is the first step that must occur in DNA replication?
Unwinding of the DNA double helix
What makes up the sides of a DNA molecule?
Deoxyribose and phosphate group
How many base pairs are in a full turn or twist of a DNA molecule?
10.5 base pairs
What are the building blocks of DNA?
Deoxyribose, nitrogenous base, and a phosphate group
What does DNA stand for?
Deoxyribonucleic acid
Which of the following modifications involves the addition of a phosphate group to a protein?
Phosphorylation
Which of the following amino acid residues are involved in modification?
Lysine, Serine, Arginine
How are histone modifications spread on a chromosome?
In a specific pattern
What is the histone code hypothesis?
A hypothesis about the role of histones in gene expression
What is epigenetic inheritance?
Inheritance of phenotypic changes in a cell or organism that do not result from changes in the nucleotide sequence of DNA
Do prokaryotes have histones?
Yes, all prokaryotes have histones except for some members of the domain Archaebacteria
How many types of histones are there in eukaryotes?
5
What is telomerase?
An enzyme that elongates telomeres
What are LINES and SINES?
Repetitive elements
What is the function of a chromatin remodeling complex?
To alter the position of nucleosomes along DNA
Which enzyme uses the energy of ATP hydrolysis to separate the two strands of nucleotides on DNA?
DNA helicase
What is the major enzyme involved in chromosome replication in E. coli?
DNA polymerase III
What is the function of topoisomerases?
To relieve tension built up by the unwinding of DNA
What is the role of a single strand DNA-binding protein in DNA replication?
To prevent base pairs from re-forming before the lagging strand can be replicated
What are Okazaki fragments?
Short length of DNA produced on the lagging strand during DNA replication
What is the average length of Okazaki fragments in prokaryotes?
100-200 nucleotides
What is the direction of DNA synthesis?
5' to 3'
What is the function of Primase in DNA replication?
To produce an RNA fragment that serves as a primer for DNA synthesis
What is the proofreading function of DNA polymerase?
To check each nucleotide during DNA synthesis and excise mismatched nucleotides
What are the differences and similarities of DNA replication in eukaryotes and prokaryotes?
Eukaryotes have multiple origins of replication, while prokaryotes have a single origin
Study Notes
DNA Structure
- DNA molecule sides are made up of deoxyribonucleotides
- A full turn or twist of a DNA molecule contains 10 base pairs
- The major and minor grooves of DNA are formed due to the double helix structure
DNA Replication
- The first step that must occur in DNA replication is unwinding of the DNA double helix
- Helicase is the enzyme that unwinds the DNA double helix during replication
- The energy of ATP hydrolysis is used by helicase to separate the two strands of DNA
- Topoisomerase is the enzyme that relieves the buildup of torque while unwinding the DNA double helix
- Primase is the enzyme that synthesizes RNA primers in DNA replication
- DNA polymerase is the enzyme that synthesizes new DNA strands by adding nucleotides to the template strand
- The function of DNA polymerase III in DNA replication is to synthesize the leading strand continuously
- The function of DNA polymerase I in DNA replication is to repair and fill in gaps
- The proofreading function of DNA polymerase is to correct errors during DNA synthesis
DNA Components
- DNA stands for Deoxyribonucleic acid
- The building blocks of DNA are deoxyribonucleotides
- Deoxyribonucleotides are made up of a sugar molecule, a phosphate group, and one of four nitrogenous bases - A, C, G, and T
Epigenetic Inheritance
- The 'histone code' hypothesis proposes that histone modifications are a key component of epigenetic inheritance
- Epigenetic inheritance is the transmission of genetic information through mechanisms other than the DNA sequence
- Histone modifications involve the addition of a phosphate group to a protein
- Serine and threonine residues are involved in histone modifications
- Histone modifications are spread on a chromosome through the recruitment of chromatin-modifying enzymes
- Prokaryotes do not have histones, but eukaryotes have five main types of histones - H1, H2A, H2B, H3, and H4
Other Concepts
- Telomerase is the enzyme that adds repetitive sequences to the ends of chromosomes
- LINES and SINES are types of repetitive elements found in the human genome
- Chromatin remodeling complexes are enzymes that use the energy of ATP hydrolysis to reorganize chromatin structure
- Single-strand DNA-binding proteins are involved in protecting single-stranded DNA during replication
- Okazaki fragments are short, discontinuous strands of DNA synthesized in the lagging strand during replication
- The average length of Okazaki fragments in prokaryotes is 1000-2000 nucleotides
- DNA synthesis always occurs in the 5' to 3' direction
Test your knowledge of DNA with this study guide quiz! Learn about the structure and composition of DNA, including the building blocks and their functions. Challenge yourself with questions on key concepts like the meaning of DNA and the components that make it up. Perfect for biology students and DNA enthusiasts!
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