GENES AND GENOMES

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Questions and Answers

Which type of satellite DNA consists of repeats that extend over millions of base pairs and is primarily found in centromeres?

Interspersed Repeat

Satellite (correct)

Microsatellite

Minisatellite

What is the primary function of Alu elements within the human genome?

Act as markers for DNA fingerprinting

Contribute to mitochondrial replication

Serve as a source of genetic variation

Play a role in unequal crossing over (correct)

Long Interspersed Nuclear Elements (LINEs) comprise what percentage of the nuclear genome?

21% (correct)

10%

0.5%

Which mechanism is primarily utilized by Class I transposons such as LINEs for their mobility?

Copy and paste Signup and view all the answers

Microsatellites are also known by which other term?

Simple Sequence Repeats Signup and view all the answers

What characteristic differentiates human protein-coding genes from prokaryotic protein-coding genes?

Eukaryotic genes contain introns, while prokaryotic genes do not. Signup and view all the answers

Which statement about prokaryotic plasmids is accurate?

They replicate independently from the main bacterial chromosome. Signup and view all the answers

What feature is unique to the human mitochondrial genome when compared with the nuclear genome?

It has a higher gene density. Signup and view all the answers

Which of the following represents a key difference between human chromosomes and prokaryotic genomes?

Human chromosomes are condensed only during cell division. Signup and view all the answers

Which statement is incorrect regarding the structural organization of eukaryotic chromosomes?

All eukaryotic chromosomes condense before DNA replication. Signup and view all the answers

What is the main substance that composes satellite DNA?

Repeated sequences in DNA. Signup and view all the answers

What is the approximate size of the human nuclear genome compared to prokaryotic genomes?

About 1000 times larger than prokaryotic genomes. Signup and view all the answers

Which aspect of prokaryotic gene arrangement is characteristic?

They are organized into closely spaced clusters. Signup and view all the answers

Which statement best reflects the nature of genes within the eukaryotic genome?

Eukaryotic genes are often interspersed with non-coding sequences. Signup and view all the answers

What percentage of the human genome is estimated to consist of repeated sequences?

60 - 73% Signup and view all the answers

What is the primary role of regulatory DNA sequences in the genome?

They provide signals that influence transcription and translation. Signup and view all the answers

Which of the following accurately describes introns in the context of eukaryotic genes?

They are non-coding sequences that are removed during RNA processing. Signup and view all the answers

What distinguishes the mitochondrial genome from the nuclear genome?

The mitochondrial genome is circular and inherited maternally. Signup and view all the answers

Which best describes interspersed repeats in the genome?

They are segments of DNA that are repetitive and randomly distributed. Signup and view all the answers

How many protein-coding genes are estimated to be present in the human genome?

Approximately 20,000 Signup and view all the answers

Which statement is true regarding satellite DNA?

Satellite DNA is a type of repetitive DNA found throughout the genome. Signup and view all the answers

What is true about the differences in genome size between Escherichia coli and humans?

Humans have fewer protein-coding genes despite a larger genome. Signup and view all the answers

Which of the following statements accurately describes repetitive sequences in the genome?

Most repetitive DNA consists of gene families with variations. Signup and view all the answers

What is characteristic of gene families in the context of repetitive DNA?

They encompass genes that are similar but differ slightly. Signup and view all the answers

Which chromosome is associated with the α globin family?

Chromosome 16 Signup and view all the answers

How do interspersed repeats primarily differ from tandem repeats?

Interspersed repeats involve multiple sequences scattered throughout the genome. Signup and view all the answers

Which type of DNA is primarily involved in replication processes within the mitochondria?

Double-stranded DNA Signup and view all the answers

Which of the following is NOT typically classified as satellite DNA?

Gene families Signup and view all the answers

What role do repeated sequences play in chromosomal structure?

They facilitate proper chromosome alignment during division. Signup and view all the answers

The olfactory receptor gene family is an example of which aspect of genetic structure?

Repetitive gene variations Signup and view all the answers

Which characteristic feature distinguishes β globin genes from α globin genes?

Location on chromosome 11 Signup and view all the answers

Which type of DNA is responsible for nearby spatial arrangements and can influence gene expression?

Satellite DNA Signup and view all the answers

Which characteristic is associated with the concept of genetic polymorphism?

Alleles that occur in more than 1% of the population but are not the most common Signup and view all the answers

What is a distinguishing feature of mitochondrial genomes compared to nuclear genomes?

Maternal inheritance pattern Signup and view all the answers

What type of DNA primarily serves as a key tool for DNA profiling?

Satellite DNA Signup and view all the answers

Which of the following statements is true regarding interspersed repeats within genomes?

They are distributed throughout the genome rather than clustered together. Signup and view all the answers

In terms of sequence variation, which of these is considered a rare variant?

A nucleotide variation found in less than 1% of the population Signup and view all the answers

Which statement accurately describes microsatellites?

They are short, tandemly repeated sequences of 1-6 base pairs. Signup and view all the answers

What role does DNA replication play in genetic variation?

It contributes to genetic variation through random mutations occurring during the process. Signup and view all the answers

Which statement best describes the relationship between genome size and species complexity?

Genome size does not effectively predict the complexity of a species. Signup and view all the answers

Which of the following best describes a wild-type allele?

The most common allele within a particular population for a given gene. Signup and view all the answers

Which of the following types of repeats can be classified as tandem repeats?

Both microsatellites and minisatellites Signup and view all the answers

What makes bacteria antibiotic resistant and how can it be transmitted to neighboring bacteria?

Plasmid and Horizontal Transfer Signup and view all the answers

What is the difference between DNA fingerprinting and Allele Tracking?

DNA fingerprinting uses highly variable regions of DNA (usually short tandem repeats or STRs), while Allele Tracking involves following specific versions (alleles) of particular genes through a family or population. It focuses on genes that have known functions or are associated with specific traits or diseases. Signup and view all the answers

Which type of organism has more non-coding/non-protein regions?

Eukaryotic Signup and view all the answers

What is true about the Nuclear Genome?

It is linear and inherited by both parents. Signup and view all the answers

Which satellite is found in centromeres where spindles attach (kinetochore)?

Centromeric repeat satellite Signup and view all the answers

Which satellite is used for DNA markers in DNA fingerprinting and allele tracking? This satellite also has telomeric repeats and is highly variable (6-64)

Minisatellite Signup and view all the answers

Which satellite contains short tandem repeats (STRs) and simple sequence repeats (SSRs), may increase in length due to certain diseases, and can be used for DNA and allele tracking?

Microsatellite Signup and view all the answers

What types of satellite DNA are considered variable tandem repeats?

Mini and micro satellite Signup and view all the answers

What is true about Telomeres?

Contain Minisatellites, repeated at the 3' end of chromosomes, protect from shortening, and are related to aging or cancer Signup and view all the answers

What is true about Short Interspersed Nuclear Elements (SINE) for satellite DNA?

SINEs are longer in repeated sequences and present in fewer copy numbers than mini/micro satellites, contain ALU elements which are the most abundant sequences in the human genome, and play a role in unequal crossing over leading to chromosomal abnormalities. Signup and view all the answers

What is an ALU element?

Found in SINE's and most abundant sequence in the human genome, plays a role in unequal chromosome crossing over Signup and view all the answers

What is true about Long Interspersed Nuclear Elements (LINE) of satellite DNA?

They are 10x longer than SINE, small amount active and source 'jumping genes', have Class I and Class II transposase which does copy and paste mechanism, they can't copy and paste themselves but can cut themselves from DNA and change their location by inserting to different location (have transcriptase and endonuclease which makes them larger than SINE) Signup and view all the answers

What is SINE?

These are like short phrases or sentences that appear many times throughout the book, but not always in the same place or order. Alu element: The Alu element is a specific, very common "sentence" in this genomic book. It's named after a restriction enzyme called AluI that can cut it. Frequency: Extremely common - there are over a million copies in the human genome! Distribution: Scattered all over the genome, like finding the same sentence on many different pages of the book. Signup and view all the answers

Study Notes

Prokaryotic Protein-Coding Genes

Prokaryotic genes are arranged in closely spaced clusters.
These genes lack introns.
Regulatory regions are shown in green.
Prokaryotic genomes are about 1/1000 the size of the human nuclear genome.
Genes are densely arranged.

Eukaryotic Genes

Eukaryotic genes have introns.
Human nuclear genome is about 3.1 x 109 bp per genome.
It contains approximately 19,000 - 20,000 protein-coding genes.
Genes are sparse, about 1 gene per 100,000 bp.
DNA is packaged up with histone proteins.
Linear DNA is organized into 23 different pairs of chromosomes (2n, diploid), with 22 autosomal chromosomes and a sex pair that can be XX or XY.

Human Mitochondrial Genome

Circular DNA with more than 10 copies per mitochondrion and more than 1000 copies per cell.
Contains 16,500 bp per genome with 37 encoded genes.
It is gene-rich, with approximately 1 gene per 445 bp.
It is inherited maternally.
The human mitochondrial genome lacks histones.

Satellite DNA

Satellite DNA is classified based on the length of the repeat.
Satellite: 171- 68 bp repeats spanning millions of bp. This is often found in centromeres.
Minisatellite: 6 - 64 bp repeats, highly variable total repeat size (polymorphic). Minisatellites are used for DNA fingerprinting and allele tracking.
Microsatellite: Aka, Short Tandem Repeats (STRs), Simple Sequence Repeats (SSRs); 2-, 3- or 4 bp units, with a highly variable total repeat size.
Alu elements are the most abundant sequence in the human genome and can play a role in unequal crossing over.

Repetitive Sequences

Long Interspersed Nuclear Elements (LINE): Most are ~6000 bp long.
Only 0.5% to 0.1% of LINEs remain active.
LINEs include genes for reverse transcriptase and an endonuclease.
Class II transposons use a "cut and paste" mechanism and require “transposase.”

Human Genetic Variation

Human genomic sequences average ~0.1% variation.
Variations in sequence arise by mutation and then spread through the population during evolution.
Alleles are different versions of an identified gene, typically differing by a small number of nucleotides.
The wild-type allele is the most common allele for a gene within a population.
Polymorphism is an allele that is less common than the wild-type allele but occurs more than 1% of the time.
A variant refers to any change in DNA sequence.
A rare variant is found at a frequency of < 1%.

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Description

Explore the differences between prokaryotic and eukaryotic protein-coding genes, focusing on their arrangement and characteristics. This quiz also covers the unique aspects of the human mitochondrial genome and its inheritance. Test your knowledge on genomic structures and gene organization.