Genetics Quiz on DNA and Gene Expression
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Questions and Answers

What is the structural and functional unit of chromatin fiber?

  • Chromatin
  • Gene
  • Chromatid
  • Nucleosome (correct)

How many histone proteins are found in the core of a nucleosome?

  • 10
  • 4
  • 8 (correct)
  • 6

What is the approximate length of DNA based on 32 base pairs?

  • 0.34 µm
  • 1.5-2 µm (correct)
  • 32 µm
  • 5-20 µm

What is the total number of genes present in the genome?

<p>12,500 (D)</p> Signup and view all the answers

What is formed by wrapping 146 base pairs around a histone protein?

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

What is the correct order of the processes described in the central dogma?

<p>DNA Transcription → mRNA Translation → Protein (D)</p> Signup and view all the answers

Which statement about DNA is accurate?

<p>DNA does not leave the nucleus. (C)</p> Signup and view all the answers

What is the purpose of reverse transcription?

<p>To convert mRNA to DNA. (A)</p> Signup and view all the answers

What percentage of the genome is typically represented by euchromatin?

<p>2% (C)</p> Signup and view all the answers

What happens prior to cell division?

<p>Replication of DNA occurs. (B)</p> Signup and view all the answers

Where does gene expression primarily occur?

<p>In the cell nucleus (C)</p> Signup and view all the answers

What is the role of helicase in the process of gene expression?

<p>To unwind the DNA molecule (C)</p> Signup and view all the answers

What type of strand does RNA polymerase transcribe from?

<p>The template strand (A)</p> Signup and view all the answers

What happens to introns during the modification of mRNA?

<p>They are removed from the mRNA (D)</p> Signup and view all the answers

What is the significance of the mature mRNA molecule?

<p>It travels to the ribosome for protein synthesis. (B)</p> Signup and view all the answers

What is splicing primarily responsible for in the mRNA molecule?

<p>Joining exons and removing introns (A)</p> Signup and view all the answers

What does the addition of a poly(A) tail to mRNA involve?

<p>Adding 100-250 adenine nucleotides (A)</p> Signup and view all the answers

Which of the following modifications involves the addition of a 5' cap?

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

What is the role of introns in the splicing process?

<p>They are removed during splicing (C)</p> Signup and view all the answers

What is the chemical modification of guanosine known as?

<p>7-methyl Guanosine (B)</p> Signup and view all the answers

What role do nuclear pores play in relation to mRNA?

<p>They allow mRNA to exit the nucleus for translation. (D)</p> Signup and view all the answers

How do nuclear pores contribute to the protection of mRNA molecules?

<p>They protect mRNA from degradation. (D)</p> Signup and view all the answers

What is a consequence of malfunctioning nuclear pores?

<p>mRNA cannot exit the nucleus. (B)</p> Signup and view all the answers

What is one function of nuclear pores stated in the document?

<p>Increase lifespan of the cell. (C)</p> Signup and view all the answers

What happens to mRNA without the function of nuclear pores?

<p>mRNA cannot exit the nucleus. (B)</p> Signup and view all the answers

What percentage of a cell's life is spent in interphase?

<p>93% (B)</p> Signup and view all the answers

Which process is responsible for the formation of gametes?

<p>Meiosis (C)</p> Signup and view all the answers

During which phase does the replication of chromosomes occur?

<p>S Phase (C)</p> Signup and view all the answers

Which type of cell division occurs in prokaryotes?

<p>Binary fission (C)</p> Signup and view all the answers

What happens during the G1 Phase of the cell cycle?

<p>Cell increases in size (C)</p> Signup and view all the answers

What is the main purpose of mitosis in a cell?

<p>To divide the cell nucleus into two identical nuclei (C)</p> Signup and view all the answers

Which phase of mitosis involves the chromosomes becoming visible and condensed?

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

What follows the completion of mitosis in the cell division process?

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

During which phase of mitosis do sister chromatids separate?

<p>Anaphase (C)</p> Signup and view all the answers

How many main steps are there in the process of mitosis?

<p>Two main steps (C)</p> Signup and view all the answers

What happens during metaphase in cell division?

<p>Chromosomes line up at the center of the cell. (C)</p> Signup and view all the answers

What is the role of spindle fibers during anaphase?

<p>They pull sister chromatids toward opposite poles. (C)</p> Signup and view all the answers

What occurs right after the centromeres split during anaphase?

<p>Sister chromatids become individual chromosomes. (B)</p> Signup and view all the answers

Which of the following correctly describes the initial stage of cell division?

<p>The spindle fibers form between the centrioles. (D)</p> Signup and view all the answers

What is the function of centrioles during cell division?

<p>They migrate to opposite ends of the cell. (D)</p> Signup and view all the answers

What is the primary function of cytokinesis in cell division?

<p>Divide the cytoplasm (C)</p> Signup and view all the answers

Which of the following events occurs during telophase?

<p>Nuclear envelope reforms (C)</p> Signup and view all the answers

What is the main outcome of meiosis?

<p>Halving the chromosome number (D)</p> Signup and view all the answers

Which structure forms to aid in the division of the parent cell during cytokinesis?

<p>Cleavage furrow (D)</p> Signup and view all the answers

Which phase of cell division is characterized by the uncoiling of chromosomes?

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

What is the main product of meiosis?

<p>Four haploid cells (D)</p> Signup and view all the answers

Which phase of meiosis involves the formation of tetrads?

<p>Prophase I (D)</p> Signup and view all the answers

How many times does cell division occur during meiosis?

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

What occurs during interphase before meiosis begins?

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

Which of the following phases is NOT part of meiosis?

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

Flashcards

DNA length in cell nucleus

DNA is too long to fit into the nucleus, needing to condense, and its length is approximately 1.5-2µm, based on 0.34Å per base pair.

Genome

All the DNA within a cell constitutes the cell's genome.

Gene count estimate

A human genome contains approximately 12,500 genes.

Nucleosome

Fundamental unit of chromatin; a segment of DNA wound around histone proteins.

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Histone core

A cluster of eight histone proteins in a nucleosome.

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Chromatin fiber

The structural form of DNA in the nucleus consisting of nucleosomes.

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Gene Expression Location

Gene expression primarily occurs inside the cell nucleus.

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mRNA Copying

Gene expression involves copying small segments of DNA into mRNA molecules.

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DNA Unwinding

During gene expression, DNA is uncoiled to expose the genetic code for copying.

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RNA Polymerase Role

RNA polymerase is the enzyme that facilitates the building of mRNA from the DNA template.

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Sense Strand (DNA)

The DNA strand used as a template for mRNA synthesis; oriented 3'→5'.

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Non-sense Strand (DNA)

The DNA strand that is not used as a template for mRNA synthesis; oriented 5'→3'.

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Central Dogma

DNA makes RNA, RNA makes protein, the flow of genetic information.

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DNA Transcription

The process of creating RNA from a DNA template.

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mRNA Translation

The process of creating a protein from an mRNA template.

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Protein (cell specific)

Proteins are crucial for cell functions, determined by the cell type.

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DNA location

DNA remains within the cell nucleus.

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Reverse Transcription

RNA is used as a template to make DNA.

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DNA Replication

Creating a copy of DNA.

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Genome

Complete set of genetic material.

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Gene Expression

Using DNA code to make a product (protein).

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Euchromatin

Active DNA, visible form, less condensed.

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Splicing

Joining exons and removing introns during RNA processing to create mature mRNA.

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Exons

Coding segments of DNA that are translated into protein.

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Introns

Non-coding segments of DNA that are removed during RNA processing.

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7-methyl Guanosine

A modification adding a methyl group to the guanosine at the 5' end of mRNA.

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Polyadenylation

Adding a poly(A) tail (adenines) to the 3' end of mRNA.

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Capping

Adding a modified guanine nucleotide (5' cap) to the 5' end of mRNA.

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Nuclear Pore Function

Nuclear pores facilitate mRNA's exit from the nucleus for protein synthesis.

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mRNA Protection

Nuclear pores shield mRNA from breakdown in the cytoplasm.

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mRNA Exit

Nuclear pores allow mRNA to leave the nucleus to be used in translation.

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Nuclear Pore Lifespan Impact

Nuclear pores influence the lifespan of the cell by supporting crucial processes like mRNA action.

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Cell Division Types

Prokaryotes divide through binary fission; eukaryotes use mitosis for somatic cells and meiosis for gamete formation.

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Cell Cycle - Interphase

The cell grows, DNA replicates, and organelles duplicate during interphase – the longest part of the cell cycle.

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G1 Phase

The first phase of interphase where the cell grows and matures.

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S Phase

DNA replication happens during the S phase of interphase.

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Mitosis Phases

The four main stages of nuclear division in cell division: Prophase, Metaphase, Anaphase, Telophase

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Prophase (Mitosis)

The first stage where chromosomes become visible and condense.

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Cytokinesis

The process where the cytoplasm divides to form two separate cells.

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Mitosis

Cell nucleus divides into two equal parts, identical copies

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Interphase

Cell grows and prepares before mitosis starts.

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Telophase

The final stage of mitosis where chromosomes uncoil, nuclear envelopes reform, spindle fibers dissolve, and cytokinesis begins.

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Cytokinesis

The division of the cytoplasm during cell division, resulting in two daughter cells, each identical to the parent cell.

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Meiosis

A type of cell division that produces gametes (sex cells) with half the number of chromosomes of the parent cell.

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Chromatid Separates

During cell division, the duplicated chromosomes (chromatids) pull apart and move to opposite sides of the cell.

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Centriole Migration

Centrioles move to opposite ends of the cell during cell division.

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Spindle Formation

Spindle fibers develop between centrioles in the dividing cell.

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Metaphase

Chromosomes line up in the center of the cell (equator).

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Anaphase

Sister chromatids separate and are pulled to opposite poles.

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Sister Chromatids

Identical copies of a chromosome.

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Meiosis

A type of cell division that produces four genetically different haploid cells (half the number of chromosomes) from one diploid cell (full number of chromosomes).

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Zygote

A fertilized egg; a diploid cell formed by the fusion of sperm and egg.

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Meiosis Phases

Meiosis has eight phases occurring in two rounds of division (Meiosis I and Meiosis II). Each round involves prophase, metaphase, anaphase, telophase, and cytokinesis.

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Interphase (meiosis)

Phase before meiosis, chromosomes duplicate, forming sister chromatids.

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Prophase I (meiosis)

Homologous chromosomes pair up, forming tetrads; crossing over occurs.

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Tetrad formation

Homologous pairs of chromosomes physically associate to make a structure called a tetrad.

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