Medical Genetics Overview

Questions and Answers

What is the primary function of genetics as a branch of science?

To analyze the chemical composition of DNA

To examine environmental impacts on evolution

To understand inheritance and expression of genetic material (correct)

To study the physical structure of the cell

Which of the following describes DNA?

It is a polymer made up of nucleotides (correct)

It exists as a single stranded molecule in all organisms

It functions only as a carrier of energy in cells

It is composed solely of amino acids

What type of bond forms between adenine and thymine in DNA?

Two hydrogen bonds (correct)

Single covalent bond

Three hydrogen bonds

Ionic bond

What is the role of the phosphate group in DNA structure?

It contributes to the DNA's negative charge Signup and view all the answers

Which statement about double-stranded DNA is correct?

It has a sugar-phosphate backbone that forms a double helix Signup and view all the answers

How are nucleotides arranged in DNA?

In a linear sequence based on genetic information Signup and view all the answers

Which pairing of nitrogenous bases is correctly matched based on their bonding?

A-T has two hydrogen bonds Signup and view all the answers

How does DNA pack into chromosomes?

By wrapping around proteins Signup and view all the answers

What is the basic structural unit of chromatin?

Nucleosome Signup and view all the answers

Which of the following describes the organization of DNA in the nucleus during interphase?

Chromatin is decondensed and individual chromosomes cannot be distinguished. Signup and view all the answers

What term refers to the DNA that is located between nucleosomes?

Linker DNA Signup and view all the answers

How many chromosomes are present in a human somatic cell?

46 chromosomes Signup and view all the answers

What is the primary function of mitochondrial DNA?

ATP production within mitochondria Signup and view all the answers

What classification of chromosomes is based on the centromeric position?

Metacentric, submetacentric, and acrocentric chromosomes Signup and view all the answers

What characterizes single copy DNA sequences in the nuclear genome?

They are present only once or a few times and include protein coding genes. Signup and view all the answers

What are the two main components of chromatin?

DNA and proteins Signup and view all the answers

During cell division, how are chromosomes structured?

In a highly condensed rod-shaped structure. Signup and view all the answers

What is the role of the histone protein H1 in chromatin?

Interacting with linker DNA. Signup and view all the answers

Study Notes

Genetics Overview

Genetics studies the nature, transmission, and expression of genetic material.
Medical Genetics focuses on inheritance, diagnosis, and treatment of genetically influenced diseases.

Genetic Material: DNA

DNA (Deoxyribonucleic Acid) is the primary genetic material in cells.
Structured as a polymer made of nucleotides comprising:
- Pentose sugar (deoxyribose)
- Nitrogenous bases (A, T, C, G)
- Phosphate group (negatively charged)

DNA Structure

Nucleotides consist of:
- Purines: Adenine (A) and Guanine (G)
- Pyrimidines: Thymine (T) and Cytosine (C)
Base pairing:
- A pairs with T via two hydrogen bonds
- C pairs with G via three hydrogen bonds
DNA exists as single or double-stranded forming a double helix, with antiparallel strands (5’ to 3’ ends).

Measuring DNA

Base pair (bp) is the basic unit for measuring DNA length.
1 kb (kilobase) equals 1000 bp.

Chromatin Packaging

DNA is wrapped around histone proteins to form chromatin, with packaging levels:
- Nucleosome: DNA (140 bp) wraps around histones
- Solenoid: Coiling of nucleosomes into 30 nm fibers
- Loop domains: Loops of chromatin fibers bind to scaffolding proteins

Chromosome Structure

Chromosomes consist of two sister chromatids joined at the centromere.
Types of chromosomes based on centromeric position:
- Metacentric
- Submetacentric
- Acrocentric

Human Chromosome Characteristics

Somatic cells contain 46 chromosomes (diploid, 2n), including 22 pairs of autosomes and 2 sex chromosomes.
Germ cells (sperm and ova) contain 23 chromosomes (haploid, n), including 22 autosomes and 1 sex chromosome.

Human Genome Organization

Human genome contains both nuclear DNA (in chromosomes) and mitochondrial DNA.
Mitochondrial DNA:
- Circular and approximately 16 kb long
- Encodes 37 genes primarily for mitochondrial function, mainly ATP production
- Mitochondrial replication is controlled by nuclear DNA.

Nuclear Genome Structure

Comprises single copy DNA sequences and repetitive DNA sequences.
Single copy DNA includes protein-coding genes and regulatory elements, often present once or a few times.
Repetitive DNA sequences are repeated extensively, aiding in chromosome structure and individual variation.

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Description

This quiz explores the fundamentals of Medical Genetics, focusing on genetic material, chromatin packaging, chromosomes, and human genome organization. It aims to deepen understanding of how genetics pertains to both science and medicine.