Genetics and Immunology Quiz

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Questions and Answers

Which type of DNA makes up the largest portion of the human genome?

Exons

Dispersed repetitive DNA (correct)

SINEs

LINEs

What percentage of the genome is composed of exons?

1-2% (correct)

90%

10%

45%

Which of the following is true about LINEs (Long Interspersed Elements)?

They are only found in certain chromosomes.

They are clustered in specific regions.

They make up about 10% of the genome.

They are longer DNA sequences, up to 7,000 bp. (correct)

What are introns primarily characterized as?

Non-coding regions within genes. Signup and view all the answers

Which component of the human genome accounts for approximately 10%?

SINEs Signup and view all the answers

What role do tandem repeats play in the human genome?

They act mainly as structural components in chromosomes. Signup and view all the answers

What is the combined percentage of repetitive DNA (SINEs, LINEs, and other repeats) in the human genome?

90% Signup and view all the answers

Which of the following is considered a single-copy DNA?

Exons Signup and view all the answers

How are SINEs defined in terms of length?

90 to 500 base pairs Signup and view all the answers

Which category of DNA constitutes the smallest portion of the human genome?

Exons Signup and view all the answers

What is the primary reason for DNA compaction within a cell nucleus?

To fit the extensive length of DNA into a small space. Signup and view all the answers

Which structure forms when nucleosomes coil together?

Solenoid structure Signup and view all the answers

What role do histone tails play in gene expression?

They can be modified to loosen or tighten DNA wrapping. Signup and view all the answers

Which enzyme is responsible for adding acetyl groups to histones?

Histone Acetyltransferase (HAT) Signup and view all the answers

What is the effect of methylation on DNA wrapping around histones?

It tightens DNA and can silence genes. Signup and view all the answers

What is euchromatin characterized by when compared to heterochromatin?

Loose structure and actively transcribed Signup and view all the answers

What function do scaffold proteins serve in chromatin organization?

They support the formation of chromatin loops. Signup and view all the answers

Which of the following does NOT contribute to DNA accessibility for transcription?

Heterochromatin formation Signup and view all the answers

Which of the following statements about nucleosomes is true?

Nucleosomes form the basic unit of DNA compaction. Signup and view all the answers

What does the modification of histone tails usually result in?

Regulation of gene activity by altering DNA wrapping. Signup and view all the answers

What is the primary role of DNA helicase in DNA replication?

To separate the double helix into two single strands Signup and view all the answers

Which enzyme is responsible for adding new nucleotides during the elongation phase of DNA replication?

DNA polymerase Signup and view all the answers

What type of fragments are formed on the lagging strand during DNA replication?

Okazaki fragments Signup and view all the answers

How does DNA polymerase ensure accuracy during DNA replication?

Through exonuclease activity for proofreading Signup and view all the answers

What challenge does topoisomerase address during DNA replication?

Supercoiling of DNA ahead of the replication fork Signup and view all the answers

What is the significance of the pyrophosphate that is released during nucleotide attachment?

It provides energy for forming the DNA bond Signup and view all the answers

What function do single-stranded binding proteins (SSBs) serve during DNA replication?

To prevent the strands from re-annealing Signup and view all the answers

What is the error rate during DNA replication?

About 1 error per ten billion nucleotides Signup and view all the answers

Which type of topoisomerase makes double-strand breaks to resolve DNA tangling?

Type II topoisomerase Signup and view all the answers

What part of the newly synthesized DNA strand is DNA polymerase adding new nucleotides to?

3’ end Signup and view all the answers

Study Notes

Genetics, Immunology and Molecular Biology

The course will be split into two parts:
- First, essential molecular biology and cytogenetics.
- Second, a deep dive into the immune system.
Both parts will build on knowledge gained during Human Biology.

Brief revision of relevant Human Biology topics:
- DNA structure and function
- Organisation of the human genome
- DNA replication
- Cell cycle and mitosis/meiosis
- RNA structure and function
- RNA synthesis, processing and modifications
- Regulation of gene expression and epigenetics
- Protein biosynthesis, modification and inhibitors
- Chromosomes and karyotyping
- Chromosome abnormalities (numerical and structural).
Mendelian inheritance:
- Variations in dominant and recessive inheritance
- Mitochondrial disorders
Population genetics
Complex Diseases: Polygenic and Multifactorial Inheritance
Complex Diseases II: Congenital and adult-onset complex diseases
Prenatal diagnosis
Genetic services
Genetic basis of cancer
Genetics and Precision Medicine

Cell Biology Revision

This section will review basic cell biology concepts.

Introduction to Cellular Biology

Cells are the fundamental units of life, each with specialised functions for organism survival.
Understanding cellular diversity helps comprehend biological complexity at a microscopic level.
Studying diverse cell types provides insights into physiological processes and disease mechanisms, crucial for targeted medical interventions.

In-depth Exploration of Cell Types

Somatic Cells:
- Major component of the body's cellular makeup.
- Perform various functions, from structural support to metabolic processes.
- Examples:
  - Neurons: Rapid signal transmission.
  - Muscle cells: Contraction and force generation.
Germ Cells:
- Specialised for sexual reproduction.
- Carry half the genetic load of somatic cells, crucial for genetic diversity.
- Examples:
  - Oocytes: Larger, nutrient-rich, support early embryonic development.
  - Spermatozoa: Highly motile, optimal delivery of genetic material.

Comprehensive Overview of Organelles

Nucleus:
- Controls gene expression and mediates DNA replication.
- Aberrations in nuclear function can lead to uncontrolled cell division (e.g., cancers).
Mitochondria:
- Site of Krebs cycle and oxidative phosphorylation.
- Crucial for energy (ATP) production.
- Mitochondrial disorders affect energy-dependent organs (e.g., neuromuscular diseases).

Endoplasmic Reticulum (ER)

Crucial for protein and lipid synthesis.
Rough ER involved in protein folding and quality control.
Smooth ER involved in lipid metabolism and detoxification.
Associated disorders include metabolic syndromes and protein folding disorders.

Golgi Apparatus

Modifies proteins received from the ER.
Involved in protein sorting and dispatching to their destinations.
Errors can lead to disorders (e.g., congenital glycosylation).

Lysosomes

Contain acid hydrolases to degrade biomolecules.
Essential for recycling cellular waste.
Defects cause lysosomal storage disorders (e.g., Gaucher's disease).

Molecular Biology Revision

DNA structure:
- 5' and 3' terminology, sugar-phosphate backbone, base pairs
Chargaff's rules of base pairing: specific ratios for nitrogenous bases in DNA
DNA double helix structure (major and minor grooves)
Types of DNA:
- Dispersed repetitive DNA (45%)
- SINEs (Short Interspersed elements): Alu repeat element
- LINEs (Long Interspersed elements)
- Exons (coding sequences)
- Introns (non-coding)

DNA Replication

Human DNA polymerase is slow (40-50 nucleotides/sec). Chromosomes have 250 million nucleotides.
Multiple origins of replication are needed to avoid long replication times.
Replication is semi-conservative (each new DNA molecule has an old and new strand).
The processes and enzymes involved in accurate replication and proofreading.
Steps of DNA replication: unwinding, stabilizing, primer synthesis, elongation, joining fragments, proofreading errors

Histone Tail Modification

N-terminal histone tails regulate transcription.
Histone Acetyltransferases (HATs) and Deacetylases (HDACs).
Histone Methyltransferases (HMTs)

DNA Replication is Very Accurate

Enzymatic mechanisms correct errors (about 1 per 10¹⁰ nucleotides).
Mismatched nucleotide translocation is prevented.
Proofreading activity increases accuracy.
Exonuclease activity degrades nucleotides.
Endonuclease activity cleaves nucleotides.

DNA Polymerase

Proofreading activity ensures accuracy (10^-2 to 10^-3 fold increase).
Removes mispaired nucleotides during replication.

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Description

Test your knowledge on essential molecular biology, cytogenetics, and the immune system. This quiz covers topics including DNA structure, gene expression, and Mendelian inheritance, building upon your Human Biology foundation. Dive into complex diseases and population genetics to assess your understanding.