Grade 12 Life Sciences: DNA and Meiosis
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Questions and Answers

Who is identified as the biological father of the child?

  • Male 1
  • Male 4
  • Male 3 (correct)
  • Male 2

What is one precaution that should be taken to avoid contamination when handling DNA samples?

  • Use unwashed equipment from previous experiments
  • Store samples in non-sterile containers
  • Mark the samples clearly to avoid mix-ups (correct)
  • Keep samples exposed to the air

Which two individuals are identified as identical twins from the DNA profiles?

  • A and B
  • B and D
  • E and D
  • C and F (correct)

Who are identified as the parents of person B based on the DNA profiles?

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

What are the potential concerns related to collecting DNA from every citizen to create a DNA profile database?

<p>It raises ethical issues and privacy concerns (A)</p> Signup and view all the answers

What is the product formed during transcription?

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

How many templates are used in the process of DNA replication?

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

Which molecule carries amino acids during protein synthesis?

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

What does a codon in an mRNA molecule represent?

<p>A specific amino acid (D)</p> Signup and view all the answers

What occurs at the ribosomes during protein synthesis?

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

How many codons are typically shown in a sequence of mRNA?

<p>3 (D)</p> Signup and view all the answers

What is the relationship between amino acids and codons?

<p>1 amino acid is coded by 1 codon (C)</p> Signup and view all the answers

Which of the following correctly represents a sequence of bases during DNA synthesis?

<p>A-T and C-G (D)</p> Signup and view all the answers

What occurs during Prophase I of meiosis that contributes to genetic variation?

<p>Homologous chromosomes pair and undergo crossing over. (C)</p> Signup and view all the answers

What is the result of crossing over during meiosis?

<p>Genetic variation is introduced among the resulting cells. (B)</p> Signup and view all the answers

At which stage of meiosis do homologous chromosomes separate and move to opposite poles?

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

What is true about the daughter cells formed after Telophase I?

<p>They are haploid and genetically varied. (C)</p> Signup and view all the answers

During which phase do spindle fibers attach to the chromosomes in meiosis?

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

Which statement accurately describes the chromosome composition after the first meiotic division?

<p>Each daughter cell receives one chromosome from each homologous pair. (D)</p> Signup and view all the answers

What happens during Metaphase I of meiosis that enhances genetic diversity?

<p>Independent assortment occurs. (D)</p> Signup and view all the answers

What is the primary function of meiosis in organisms?

<p>To create genetic variation in gametes. (C)</p> Signup and view all the answers

What is a biological importance of DNA replication?

<p>It ensures the preservation of genetic information. (D)</p> Signup and view all the answers

How does a mutation that alters a DNA codon affect protein synthesis?

<p>It can lead to the production of a different protein. (C)</p> Signup and view all the answers

Which statement describes the outcome of a single nucleotide change in DNA?

<p>It may result in a different amino acid being included. (D)</p> Signup and view all the answers

What describes a mutation involving adenine being changed to cytosine?

<p>A point mutation that can affect protein structure. (D)</p> Signup and view all the answers

In the event of a codon change from AUA to AUU, what is the expected consequence?

<p>The resulting protein may differ due to the amino acid change. (D)</p> Signup and view all the answers

What is an example of a result from DNA replication mistakes?

<p>Gene mutations that can affect the phenotype. (D)</p> Signup and view all the answers

What defines the nature of a mutation that leads to a significant change in protein function?

<p>It can result in a single amino acid substitution. (D)</p> Signup and view all the answers

Which mutation type can introduce a completely different protein into an organism?

<p>A frameshift mutation shifting the reading frame. (A)</p> Signup and view all the answers

What type of chromosome is structure B considered to be?

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

During which phase of meiosis does non-disjunction occur?

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

How many chromosomes are present in a normal gamete formed after meiosis?

<p>23 (B)</p> Signup and view all the answers

What type of mutation involves a change in the structure and number of chromosomes?

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

What is the primary distinction between structure B and structure C?

<p>Structure B is made of two chromatids, while structure C is made of one chromatid. (D)</p> Signup and view all the answers

What process is depicted at location A in the diagram of meiosis?

<p>Non-disjunction (A)</p> Signup and view all the answers

What separates during Anaphase I of meiosis?

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

How many pairs of chromosomes are typically present in a normal human sperm cell?

<p>23 (B)</p> Signup and view all the answers

Which part of a chromosome attaches to the spindle fibres during cell division?

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

Which part of the chromosome directly represents a gene?

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

What is the phase of meiosis represented in a typical early diagram during prophase?

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

Identify the phase of meiosis represented in a diagram showing alignment at the cell's equator.

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

Which part of the cell contains the DNA during meiosis?

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

What forms the spindle fibres during meiosis?

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

What is the name of the process during which genetic material is exchanged between homologous chromosomes?

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

Flashcards

Paternity Testing

Comparing DNA profiles can be used to determine if an individual is the biological father of a child.

DNA Sample Handling

Precautions must be taken when handling DNA samples to avoid contamination with other DNA.

DNA Profiling

DNA profiling is used to identify individuals by comparing their unique genetic profiles.

Identical Twins DNA

Identical twins share the same DNA profile, meaning they are genetically identical.

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DNA Database for All Citizens

A database containing DNA profiles of all citizens raises ethical concerns about privacy and potential misuse of the information.

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Transcription

The process of creating mRNA from a DNA template.

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Translation

The process of using mRNA to build proteins.

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Codon

A three-nucleotide sequence on mRNA that codes for a specific amino acid.

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Anticodon

A three-nucleotide sequence on tRNA that complements a codon on mRNA.

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tRNA

A molecule that carries amino acids to the ribosome during translation.

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Ribosome

The site of protein synthesis where mRNA and tRNA interact to create a polypeptide chain.

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Polypeptide

A chain of amino acids linked together by peptide bonds.

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Purpose of Codons

The sequence of codons in a mRNA molecule determines the order of amino acids in the polypeptide chain.

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What is a gene mutation?

A change in the sequence of DNA nucleotides that can lead to alterations in the amino acid sequence of a protein, potentially affecting its function.

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How can DNA replication lead to a gene mutation?

An error during DNA replication, where the wrong nucleotide base is incorporated into the new DNA strand, resulting in a changed base sequence.

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What is protein synthesis?

The process by which genetic information encoded in DNA is used to create a functional protein.

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What is a point mutation?

A change in a single nucleotide base within a DNA sequence, which can alter the corresponding mRNA codon and potentially result in a different amino acid being incorporated into the protein.

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What is a silent mutation?

A mutation that results in a codon that still codes for the same amino acid, therefore not affecting the protein's structure or function.

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What is a missense mutation?

A mutation that results in a codon that codes for a different amino acid, potentially altering the protein's structure or function.

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What is a nonsense mutation?

A mutation that changes a codon that codes for an amino acid into a stop codon, truncating the protein and potentially making it non-functional.

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What is a frameshift mutation?

A mutation that involves the insertion or deletion of one or more nucleotides, leading to a frameshift in the reading frame and potentially altering the entire amino acid sequence downstream of the mutation.

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What is a bivalent?

Two homologous chromosomes, each composed of two sister chromatids, paired up during prophase I of meiosis. The pairing allows for the exchange of genetic material through crossing over.

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What is a chiasma?

The point where non-sister chromatids (from different chromosomes) of a homologous pair exchange genetic material during prophase I of meiosis.

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What is crossing over?

The process of exchanging genetic material between non-sister chromatids of a homologous pair during prophase I of meiosis.

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What is random arrangement?

The random arrangement of homologous chromosomes at the metaphase plate during metaphase I of meiosis. This contributes to genetic variation.

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What is cytokinesis?

Division of the cytoplasm that occurs after nuclear division during both mitosis and meiosis. It results in two daughter cells.

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What is a haploid cell?

A cell with half the number of chromosomes as the original parent cell. Produced by meiosis.

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What is meiosis I?

Meiosis I is a type of cell division that produces two daughter cells, each with half the number of chromosomes as the original parent cell. This reduction in chromosome number is essential for sexual reproduction.

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What is meiosis II?

Meiosis II is a type of cell division that produces four daughter cells, each with half the number of chromosomes as the original parent cell. Meiosis II follows meiosis I and ensures the production of haploid gametes.

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Replicated Chromosome

Chromosomes are made up of two chromatids (identical DNA copies) attached at the centromere. When the chromosome duplicates (replicates), the two chromatids are held together by the centromere.

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Unreplicated Chromosome

A chromosome with only one chromatid (a single DNA molecule).

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Non-disjunction

The failure of homologous chromosomes to separate during meiosis I, leading to an uneven distribution of chromosomes in daughter cells.

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Chromosomal Mutation

A change in the structure or number of chromosomes within a cell. It can result in various genetic disorders.

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Diploid cell

A cell with two sets of chromosomes (one from each parent). For example, human somatic cells have 46 chromosomes.

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Haploid cell

A cell with a single set of chromosomes. In humans, gametes (sperm and egg) are haploid, containing 23 chromosomes.

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Anaphase I

The phase of meiosis where homologous chromosomes are separating, moving towards opposite poles of the cell.

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Horizontal gene transfer

The process where genetic material is transferred from one organism to another, often bacteria.

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How many pairs of chromosomes are in a sperm cell?

A human sperm cell contains 23 chromosomes, which exist as 23 pairs (one chromosome from each pair coming from the father and the other from the mother).

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What part of a chromosome attaches to spindle fibres?

The centromere is the region where the two sister chromatids of a chromosome are attached. It's involved in chromosome movement during cell division.

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What represents a gene?

A gene is a segment of DNA that codes for a specific protein. It determines a particular trait or characteristic.

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What phase of meiosis is represented in Diagram 1?

Diagram 1 represents prophase I, the first stage of meiosis I, where homologous chromosomes pair up and exchange genetic material.

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What phase of meiosis is represented in Diagram 3?

Diagram 3 represents the end of meiosis II, where sister chromatids have separated, resulting in four haploid daughter cells (gametes).

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What part of the cell contains DNA?

DNA is found within the chromosomes. Each chromosome is composed of a single, long DNA molecule.

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What attaches to centromeres of chromosomes ?

The centromere is the region that attaches to the spindle fibres, assisting in the separation of chromosomes during cell division.

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What forms spindle fibres?

Spindle fibres are made of microtubules and form during cell division. They extend from the poles of the cell and attach to the centromeres of chromosomes to separate them.

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Where does meiosis occur in a human male?

Meiosis occurs in the testes of a human male, where sperm cells are produced through the process.

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Study Notes

Introduction

  • This self-study guide is for Grade 12 Life Sciences students.
  • It addresses the topics of DNA, the code of life, and meiosis.
  • The guide aims to address learning gaps created by the COVID-19 pandemic.
  • The guide focuses on essential topics, skills, and concepts in Grade 12 to strengthen mastery of subject knowledge.
  • It emphasizes independent learning and mastering core cross-cutting concepts.

How to use this self-study guide

  • Five booklets cover all Grade 12 topics.
  • Booklet 1: DNA: Code of Life and Meiosis
  • Booklet 2: Reproduction in Vertebrates, Human reproduction, Endocrine System and Homeostasis
  • Booklet 3: Genetics and Inheritance
  • Booklet 4: Responding to the Environment: Humans and Plants
  • Booklet 5: Evolution: Natural Selection and Human evolution
  • Use this guide with the Life Sciences Mind the Gap Study Guide.
  • Study the content from the DBE Grade 12 Textbook, DBE Exam Guideline 2021, and Mind the Gap.
  • Master the relevant concepts and content.
  • Focus on exam techniques and tips for approaching specific question types.
  • Practice questions and answers included

DNA: The Code of Life

  • Prior knowledge: Plant and Animal cells, proteins, nucleic acids, location of DNA and chromosomes.
  • Mind map on DNA - Code of life: Covers location of RNA, structure of RNA, function of RNA, translation, transcription, protein synthesis, and DNA related aspects
  • Links to prior knowledge/Background knowledge (Examples: cell structure, organelles, functions of organelles, etc.)
  • Differentiate between related terminologies (Examples: chromatin vs. chromatids, DNA vs. RNA, genes vs. alleles, etc.)
  • DNA Replication: Exam techniques, tips, and notes, practice questions, solutions
  • DNA profiling: Exam techniques, tips, and notes, practice questions, solutions
  • Protein Synthesis: Exam techniques, tips, and notes, practice questions, solutions
  • Genetic coding: Exam techniques, tips, and notes, practice questions, solutions
  • The effect of mutation: Exam notes, practice questions, and solutions regarding how mutations affect DNA sequence and protein structure

Meiosis

  • Mind map on Meiosis
  • Links to prior knowledge/Background knowledge
  • Differentiate between related terminologies
  • Meiosis process: Exam techniques, tips, and notes, practice questions, solutions
  • Practical questions on Meiosis
  • Typical exam questions, solutions to questions

DNA Replication - Exam Tips

  • Detailed step-by-step process of DNA replication
  • Explanation of errors occurring during DNA replication (mutations).

DNA Profiling- Exam Tips

  • Explanation of DNA profiling
  • How to interpret DNA profiles (bands/bars)
  • Practical application in paternity testing and forensic investigations
  • Precautions to be taken when handling DNA samples.

Protein Synthesis - Exam Tips

  • Describes the process of transcription and translation
  • Explains the role of mRNA, tRNA, and rRNA in protein synthesis

Genetic Coding - Exam Tips

  • Definition of genetic coding
  • Importance of proteins.
  • Details on triplets (codons).

The effect of mutation on Protein Structure

  • Explanations on mutations affecting DNA and the changes that occur in protein sequences
  • Diagrams and scenarios showing how mutations affect the formation of a protein.

Practice Questions and Solutions

  • Varied practice questions (multiple choice, short answer, diagrams, etc.)
  • Solutions for DNA replication, transcription, genetic coding, and protein synthesis.
  • Solutions for DNA profiling.
  • Practice questions regarding meiosis
  • Solutions for process of meiosis questions

References

  • List of sources used for the information

Acknowledgement

  • Acknowledge the people/organizations involved in creating the guide

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Life Sciences - DNA Code of Life & Meiosis (1) Self-Study Guide PDF

Description

This self-study guide is designed for Grade 12 Life Sciences students focusing on essential topics like DNA, the code of life, and meiosis. It aims to bridge learning gaps exacerbated by the COVID-19 pandemic and supports independent mastery of critical concepts. Students will benefit from thorough coverage across five booklets, reinforcing their subject knowledge and skills.

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