Self Study Guide for Grade 12 Life Sciences

A comprehensive set of flashcards to aid in studying key concepts in DNA and meiosis from the Self Study Guide for Grade 12 Life Sciences.

What is the main focus of the Self-Study Guide for Grade 12 Life Sciences?

To help close content gaps and strengthen mastery of subject knowledge in Grade 12.

What pandemic led to the disruption of effective teaching in South Africa?

COVID-19.

How does this Self-Study Guide assist students?

By providing exams tips, techniques, and practice questions on critical topics.

How many self-study guides cover all Grade 12 topics?

Five self-study guides.

What is the topic of Booklet One in the Self-Study Guide?

DNA: Code of Life and Meiosis.

What are the two types of nucleic acids involved in the cell nucleus?

DNA and RNA.

What is the significance of the ribosome?

It is the site of protein synthesis.

How many chromosomes are found in human cells?

46 chromosomes.

What is the basic unit of DNA?

Nucleotide.

What is the process that leads to the formation of two identical DNA molecules?

DNA replication.

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

A sudden change in the DNA nucleotide sequence.

What does DNA stand for?

Deoxyribonucleic Acid.

What is the role of mRNA in protein synthesis?

It carries the genetic code from DNA to the ribosomes.

What structure surrounds the nucleus in a cell?

Nuclear membrane.

What is the significance of the process of meiosis?

It reduces the chromosome number in gametes and increases genetic diversity.

How many haploid chromosomes are present in human gametes?

23 chromosomes.

What is the role of tRNA in protein synthesis?

It brings specific amino acids to the ribosome during translation.

Define homologue in the context of chromosomes.

Chromosomes that are identical in shape and size and contain genes for the same characteristics.

What are the two main processes involved in protein synthesis?

Transcription and translation.

What base pairs with Adenine (A) in DNA?

Thymine (T).

What is the function of eukaryotic ribosomes?

To synthesize proteins by translating mRNA.

What are two components of the nucleoplasm?

Free nucleotides and enzymes.

What is meant by 'crossing over' during meiosis?

The exchange of genetic material between homologous chromosomes.

Name the process which forms mRNA from a DNA template.

Transcription.

Identify one key feature that differentiates mitosis from meiosis.

Mitosis produces two identical daughter cells while meiosis produces four genetically diverse gametes.

What is a codon?

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

What is the effect of a mutation on protein structure?

It can lead to a change in the amino acid sequence of the protein.

What is meant by complementary base pairing?

The specific pairing of nucleotide bases: Adenine with Thymine and Cytosine with Guanine.

In which part of the cell does transcription occur?

In the nucleus.

During which phase of the cell cycle does DNA replication occur?

Interphase.

What is the final product of protein synthesis?

A polypeptide chain or protein.

What are nucleotides made up of?

A pentose sugar, a phosphate group, and a nitrogenous base.

What process results in genetic variation?

Meiosis.

What is the significance of DNA profiling?

To establish paternity, identify crime suspects, and determine genetic disorders.

How many amino acids are there in the genetic code?

20 different amino acids.

What are the three types of RNA involved in protein synthesis?

mRNA, tRNA, and rRNA.

What is a genotype?

The genetic constitution of an organism.

Name a genetic disorder caused by chromosomal mutations.

Down syndrome.

What is a phenotype?

The observable physical or biochemical characteristics of an organism.

What role does the centrosome play in cell division?

It organizes the microtubules to form the spindle apparatus.

What happens during anaphase of mitosis?

Sister chromatids are pulled apart to opposite poles of the cell.

How does the structure of RNA differ from DNA?

RNA contains ribose sugar, and uracil replaces thymine.

What do anti-codons do in protein synthesis?

They pair with codons on mRNA to ensure correct amino acid incorporation.

What is the purpose of the chiasma during meiosis?

It is the site where crossing over occurs between homologous chromosomes.

What does a karyotype represent?

The number and appearance of chromosomes in the nucleus of a cell.

What is the role of enzymes in DNA replication?

Enzymes help unwind the DNA strand and synthesize the new complementary strand.

What are gametes?

Sex cells that contain half the chromosome number of somatic cells.

What is cytokinesis?

The division of the cytoplasm into two daughter cells following mitosis or meiosis.

How many steps are in the process of DNA replication?

Generally five major steps.

What is the purpose of meiosis in sexual reproduction?

To produce gametes with genetic variation.

Which protein structure is primarily formed during translation?

Polypeptide chain.

What is the function of the nuclear pore?

To regulate the transport of molecules between the nucleus and the cytoplasm.

What is the role of the nucleolus?

It is involved in the production of ribosomes.

Define polygenic inheritance.

Inheritance of traits that are controlled by multiple genes.

What is the role of chromosomes during cell division?

They ensure accurate distribution of genetic material to daughter cells.

Name one technique used in DNA profiling.

Gel electrophoresis.

What is the main purpose of a DNA molecule?

To store genetic information.

What is a heterozygous genotype?

A genotype with two different alleles for a specific gene.

How does a stop codon function in protein synthesis?

It signals the end of the polypeptide chain synthesis.

What is the difference between dominant and recessive alleles?

Dominant alleles mask the effects of recessive alleles.

What is the purpose of gel electrophoresis?

To separate DNA fragments based on size.

How many chromosomes do humans inherit from each parent?

23 chromosomes from each parent.

What occurs during telophase in mitosis?

The nuclear membrane reforms around each set of chromosomes.

What type of bonds hold the DNA double helix together?

Hydrogen bonds.

Define gametogenesis.

The process by which gametes are produced through meiosis.

What role does the p53 gene play in the cell cycle?

It acts as a tumor suppressor, preventing cell division in damaged cells.

Identify one way in which DNA profiling is used in forensics.

To match biological evidence from a crime scene with a suspect.

What is the name of the process that occurs in the synthesis of proteins where mRNA is translated into an amino acid sequence?

Translation.

What happens to the chromatin during cell division?

It condenses into visible chromosomes.

Name the process that results in the formation of four genetically diverse daughter cells.

Meiosis.

What does it mean for an organism to be homozygous?

Having two identical alleles for a specific trait.

What vitamin is essential for the repair of DNA sequences?

Vitamin B9 (folate).

What impact do mutations have on protein structure?

They can change the sequence of amino acids, potentially altering protein function.

What technique allows scientists to amplify specific segments of DNA?

Polymerase chain reaction (PCR).

How many phases are there in meiosis?

Two phases: Meiosis I and Meiosis II.

What do the terms 'haploid' and 'diploid' refer to?

Haploid cells have one set of chromosomes; diploid cells have two sets.

What is the role of centrioles during cell division?

To organize the spindle fibers necessary for chromosome separation.

During which phase of meiosis do homologous chromosomes separate?

Anaphase I.

What is the result of nondisjunction during meiosis?

An abnormal number of chromosomes in the resulting gametes.

What role does zinc play in DNA synthesis?

It is a cofactor required for the activity of DNA polymerase.

What is the difference between an intrusive mutation and an extensive mutation?

Intrusive mutations occur within a gene sequence, while extensive mutations affect large sections of chromosomes.

How do environmental factors influence mutation rates?

Certain environmental exposure can increase mutation rates (e.g., radiation, chemicals).

What is the typical duration of mitosis?

It usually takes about 30-60 minutes.

In the context of DNA, what does 'replication' entail?

The process of making an identical copy of a DNA strand.