Molecular Biology of Genes (BIOM335) Overview

Questions and Answers

What is the primary function of a gene within a chromosome?

To store genetic information

To encode a specific protein (correct)

To serve as a structural component of chromosomes

To replicate DNA during cell division

How many genes might a mycoplasma bacterium contain?

Approximately 20,000

Approximately 60,000

Approximately 500 (correct)

Approximately 25,000

What does the term 'locus' refer to in genetics?

The observable traits of an organism

The physical structure of a chromosome

The location of a gene on a chromosome (correct)

The total number of genes in an organism

What are alleles?

Sequences of DNA that are variations of the same gene Signup and view all the answers

What type of sugar is present in DNA?

Deoxyribose Signup and view all the answers

Why are homologous chromosomes important in genetics?

They carry identical sequences of genes at the same loci Signup and view all the answers

Which pairs of nitrogenous bases are correct in DNA?

Cytosine with Guanine Signup and view all the answers

Which organism is reported to have the highest number of genes among the ones referenced?

Rice Signup and view all the answers

What is the expected diameter of the DNA double helix?

20 Å Signup and view all the answers

During which phase are chromosomes visible as distinct entities?

During cell division Signup and view all the answers

Which statement about the polynucleotide chains is incorrect?

They contain ribose sugar. Signup and view all the answers

What is the correct relationship between genes, RNA, and proteins?

Genes encode RNA which may synthesize proteins Signup and view all the answers

During DNA base pairing, which base pairs with adenine?

Thymine Signup and view all the answers

What is the structure of the DNA double helix primarily characterized by?

Flat nitrogenous bases facing inward Signup and view all the answers

What is a characteristic feature of the B-form of DNA?

It is a double helix structure. Signup and view all the answers

Which of the following correctly describes a nucleotide?

A nucleoside linked to a phosphate group Signup and view all the answers

What is the primary function of structural genes?

They encode proteins for structural and functional needs. Signup and view all the answers

How much of human DNA is estimated to be composed of protein-coding genes?

Only 1% Signup and view all the answers

Which statement correctly describes non-coding DNA (ncDNA)?

It can be transcribed into functional but non-coding RNA. Signup and view all the answers

What is the product of a gene that does not encode a polypeptide?

A non-coding RNA Signup and view all the answers

What does a gene directly produce?

An RNA strand Signup and view all the answers

In the context of bacterial transformation, what does the process primarily demonstrate?

DNA acts as the genetic material of bacteria. Signup and view all the answers

Which type of RNA is directly responsible for carrying amino acids to the ribosome?

tRNA Signup and view all the answers

What role do regulator genes play in the genome?

They control the expression of structural genes. Signup and view all the answers

What is a genome?

The complete set of hereditary information carried by an organism. Signup and view all the answers

Which statement is true regarding chromosomal DNA in humans?

It is found in 23 pairs of chromosomes in the nucleus. Signup and view all the answers

What role do proteins play in the development of an organism?

They are involved in the expression of nucleotide sequences. Signup and view all the answers

What is a plasmid?

A small circular double-stranded DNA found in bacteria. Signup and view all the answers

Which element is NOT part of a genome?

Nuclear RNA. Signup and view all the answers

How many times will attendance be called during the course?

Three times per lecture. Signup and view all the answers

What type of DNA structure is characterized by having more than one turn per 10.5 base pairs?

Overwound DNA Signup and view all the answers

What is the form of DNA found in the mitochondria?

Circular DNA. Signup and view all the answers

What does semiconservative replication mean in the context of DNA replication?

One parental strand and one daughter strand form a new DNA duplex. Signup and view all the answers

What must be reported to the Advisory in case of absences?

The cause of the absence. Signup and view all the answers

Which of the following enzymes is responsible for synthesizing RNA from a DNA template?

RNA polymerase Signup and view all the answers

What is the role of polymerases in DNA replication?

To synthesize daughter strands from separated parental strands. Signup and view all the answers

What characterizes the replication fork during DNA replication?

It is where parental strands are separated and new strands are synthesized. Signup and view all the answers

Which statement correctly describes the function of endonucleases?

They cleave bonds within a nucleic acid chain. Signup and view all the answers

During which process is DNA converted into RNA?

Transcription Signup and view all the answers

What is the significance of the Meselson–Stahl experiment in understanding DNA replication?

It proved that one strand of the DNA helix is preserved in each generation. Signup and view all the answers

Study Notes

Course Overview

Molecular Biology of Genes (BIOM335) is taught by Dr. Fatima Labeed.
Syllabus available on Black Board (BB) for topic and assessment details.
Course includes two lectures weekly, approximately 60-70 minutes each.
Lecture notes/slides are regularly updated; check for the latest versions.
Assessments: Tests, assignments/presentations, midterm, and final exams.
Attendance is recorded by calling names; late arrivals may be marked absent.
Absences require reporting to the Advisory for potential excusal.

Genome and DNA Basics

Genome: Complete set of hereditary information in DNA; includes chromosomal DNA and mitochondrial DNA.
In humans, the genome consists of 23 pairs of chromosomes.
Plasmids: Small, circular double-stranded DNA found in bacteria and some eukaryotes.
Organellar DNA: Present in eukaryotes, found in mitochondria and chloroplasts.
Nucleotide: Basic building block of nucleic acids (DNA & RNA).
Proteins are essential for cellular structures, receptors, and metabolism.

Genes and Chromosomes

Chromosomes: Discrete units in the genome containing many genes; visible during cell division.
Gene count varies: Mycoplasma (∼500 genes), humans (∼20,000-25,000 genes), rice (∼50,000-60,000 genes).
Genetic locus: Specific location of a gene in a chromosome; multiple loci referred to as loci.
Homologous chromosomes carry the same gene sequences at identical loci.

The Function of Genes

Genes are fundamental units of heredity; they encode RNA and, in many cases, polypeptides.
Additionally, some genes do not code for proteins but are integral to the genome.
Approximately 1% of DNA codes for proteins; non-coding DNA includes regulatory RNAs (e.g., tRNA, microRNA).
Structural genes encode necessary proteins, while regulator genes control the expression of structural genes.

Gene Expression

Genes produce RNA, which can lead to polypeptide production or function in non-coding roles.
Understanding gene expression clarifies the gene's role as a DNA sequence that directs RNA synthesis.
Examples include rRNA and tRNA where RNA is the functional product rather than encoding proteins.

Genetic Material in Cells

DNA serves as the genetic material in all organisms and many viruses; RNA serves as genetic material in some viruses.
Bacterial transformation demonstrated DNA as the genetic material in bacteria using strains of S. pneumoniae.
Viral genome composition: DNA is main genetic material, with exceptions for RNA viruses.

Structure of DNA

DNA is a double helix consisting of two antiparallel polynucleotide chains.
Bases pairing: Adenine with Thymine (A-T) and Cytosine with Guanine (C-G); RNA uses Uracil (U) in place of Thymine.
DNA double helix dimensions: Diameter is 20 Å, one full turn every 34 Å, approximately 10.4 base pairs per turn.

DNA Replication

Replication is semiconservative, with each original strand serving as a template for a new complementary strand.
The Meselson-Stahl experiment confirmed that one strand from each parent helix is conserved in daughter strands.
DNA polymerases synthesize daughter strands at the replication fork, where parental strands are separated.
Enzymes involved in DNA processing:
- Nucleases: degrade nucleic acids, with types including endonucleases and exonucleases.

RNA and Reverse Transcription

Cellular genes are primarily composed of DNA; some viruses use RNA genomes.
Transcription: DNA is converted into RNA by RNA polymerase.
Reverse transcription: RNA is converted back into DNA.

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Description

This quiz provides an overview of the Molecular Biology of Genes course (BIOM335) taught by Dr. Fatima Labeed. It outlines the course structure, including the frequency of lectures and the assessment methods. Stay updated with the syllabus and lecture notes available on Black Board for the most current information.