Molecular Biology of the Human Genome

<p>Non-coding regions within genes (D)</p> Signup and view all the answers

<p>90% (D)</p> Signup and view all the answers

<p>Centromeres of chromosomes (A)</p> Signup and view all the answers

<p>They control how tightly or loosely DNA is packed, affecting gene activity. (C)</p> Signup and view all the answers

<p>Solenoid structure (B)</p> Signup and view all the answers

<p>Histone Acetyltransferases (HATs) (B)</p> Signup and view all the answers

<p>To fit DNA inside the cell nucleus. (D)</p> Signup and view all the answers

<p>DNA becomes tightly packed, silencing genes. (A)</p> Signup and view all the answers

<p>Euchromatin (A)</p> Signup and view all the answers

<p>150 base pairs (C)</p> Signup and view all the answers

<p>They support chromatin loops and maintain structure. (D)</p> Signup and view all the answers

<p>To proofread and correct errors in DNA synthesis (A)</p> Signup and view all the answers

<p>By cleaving one strand of DNA at the phosphodiester bond (D)</p> Signup and view all the answers

<p>A new bond is formed between the 3′-OH and 5′-phosphate (A)</p> Signup and view all the answers

<p>They prevent single-stranded DNA from folding back on itself (B)</p> Signup and view all the answers

<p>The action of cutting nucleotides from the end of the DNA strand (B)</p> Signup and view all the answers

<p>By allowing corrections that improve accuracy by 100 to 1,000 times (B)</p> Signup and view all the answers

<p>To separate the double helix into two single strands (D)</p> Signup and view all the answers

<p>They prevent the strands from re-annealing (D)</p> Signup and view all the answers

<p>DNA ligase (B)</p> Signup and view all the answers

<p>It employs a proofreading mechanism. (A)</p> Signup and view all the answers

<p>Type I (A)</p> Signup and view all the answers

<p>Two phosphates are removed as pyrophosphate. (C)</p> Signup and view all the answers

<p>It corrects incorrectly paired nucleotides. (C)</p> Signup and view all the answers

<p>The leading strand is synthesized continuously while the lagging strand is in fragments. (B)</p> Signup and view all the answers

<p>Poor fidelity of DNA synthesis (D)</p> Signup and view all the answers

<p>They regulate gene activity by altering DNA packaging. (B)</p> Signup and view all the answers

DNA sequences repeated multiple times in the genome, scattered throughout and making up nearly half (45%) of the human genome.

Short DNA sequences (90-500 base pairs) repeated throughout the genome, with Alu elements being a common example.

Longer DNA sequences (up to 7,000 base pairs) scattered throughout the genome.

Coding segments of DNA within a gene that are used to produce proteins.

Non-coding regions within genes that are not translated into proteins.

Most DNA (90%) in the human genome is repetitive or non-coding, while only a small portion (1-2%) codes for proteins.

The complex of DNA and proteins that makes up chromosomes, allowing DNA to be tightly packed into the nucleus.

A basic unit of chromatin consisting of a segment of DNA wrapped around eight histone proteins.

The protruding ends of histone proteins that can be modified to influence the tightness of DNA packaging.

The addition of an acetyl group to histone tails, loosening DNA and making genes accessible for transcription.

The addition of a methyl group to histone tails, tightening DNA and silencing genes.

Enzymes that add acetyl groups to histone tails, activating genes.

Enzymes that remove acetyl groups from histone tails, silencing genes.

Euchromatin is loose, active DNA where genes are transcribed, while heterochromatin is tightly packed, inactive DNA where genes are silenced.

The process of copying DNA to ensure that each new cell gets an exact genetic copy during cell division.

Each new DNA molecule consists of one original (old) strand and one newly synthesized strand.

The Y-shaped structure formed during DNA replication where the double helix is unwound and separated into two single strands.

An enzyme that unwinds the DNA double helix, breaking the hydrogen bonds between the base pairs.

Proteins that bind to and stabilize the separated single strands of DNA, preventing them from re-annealing.

An enzyme that synthesizes short RNA primers, providing a starting point for DNA polymerase to build new DNA strands.

An enzyme that adds new nucleotides to the 3' end of an existing DNA strand, synthesizing a new strand.

The DNA strand that is synthesized continuously in the 5' to 3' direction during replication.

The DNA strand that is synthesized discontinuously in short fragments (Okazaki fragments) in the 5' to 3' direction.

Short DNA fragments synthesized on the lagging strand during replication.

DNA polymerase can remove incorrect nucleotides from the end of a DNA strand during replication.

DNA polymerase can also remove incorrect nucleotides from the middle of a DNA strand.

DNA ligase seals the gaps (nicks) between DNA fragments by forming a phosphodiester bond, joining the 3' hydroxyl group to the 5' phosphate group.

SSBs prevent the unwound single strands of DNA from tangling or forming hairpins by binding to them, keeping them straight and ready for replication.

Type I Topoisomerase relieves overwinding stress in DNA by temporarily breaking one strand of the helix, allowing rotation, and then rejoining it.

DNA polymerase has a proofreading function that significantly increases replication accuracy by detecting and correcting errors.