Grade 12 Life Sciences - DNA, Meiosis, Reproduction, Genetics, Nervous & Endocrine Systems, Homeostasis, Plant Responses, Evolution & Human Impact

Flashcards for Grade 12 Life Sciences - DNA, Meiosis, Reproduction, Genetics, Nervous & Endocrine Systems, Homeostasis, Plant Responses, Evolution & Human Impact

What is DNA replication?

Process by which DNA makes an identical copy of itself.

When does DNA replication occur?

It occurs just before cell division (mitosis and meiosis).

Why does DNA replication occur?

To make identical copies of DNA so that it could be shared amongst the daughter cells during cell division so that each daughter cell has the same chrmosomes as the original.

What is the first step in DNA replication?

Double helix DNA unwinds, weak hydrogen bonds between nitrogenous bases break, and the two DNA strands unzip/separate.

What serves as a template³ to form a new strand in DNA replication?

Each original DNA strand serves as a template to form a new strand.

What is the immediate result of DNA replication?

Each DNA molecule consists of 1 original strand and 1 new strand, with two new genetically identical DNA molecules.

What are DNA profiles?

Patterns of black bars left on X-ray film when an extract of DNA is put through a special biotechnical process.

What is DNA profiling?

Identifying an individual by comparing his/her DNA profile with another known DNA profile.

What are the uses of DNA Profiles?

Diagnosis of inherited disorders, identification of criminals, identification of relatives, identifying people who have died.

What is Transcription?

Formation of messenger RNA (mRNA).

What happens in Transcription?

DNA double helix unwinds, weak hydrogen bonds of DNA break forming two single strands of DNA.

Where does mRNA moves out in Transcription?

mRNA moves out of the nucleus through the nuclear pore into the cytoplasm where it attaches to the ribosome.

What is Translation?

Using information from mRNA to form a protein.

What brings the required amino acids to the ribosome?

tRNA molecules with matching/complementary anticodons bring the required amino acids to the ribosome.

How is Translation completed?

The amino acids link together by peptide bonds to form the required protein.

What is Non-coding DNA?

Sections of DNA that do not carry a code for proteins.

What is Anticodon?

The triplet of bases on tRNA.

What is Chromatin network?

Tangled network of chromosomes located within the nucleus.

What is Codon?

The triplet of three consecutive bases on mRNA.

What is Cytosine?

The base that pairs off with guanine.

What is DNA?

Nucleic acid that is a constituent of chromosomes.

What is extra-nuclear DNA?

Site of DNA replication & transcription.

What is Peptide Bond?

Bond formed between two amino acids.

What is Ribosome?

Site of synthesis of proteins by the combination of amino acids.

What is RNA?

Single stranded nucleic acid.

What is Replication?

Production of identical copies of DNA.

What is Double helix?

Natural shape of a DNA molecule.

What is Template?

Strand of DNA used to form either another strand of DNA or mRNA.

What is Thymine?

The base that pairs off with adenine in DNA.

What is Extra-nuclear DNA?

DNA that only occurs outside the nucleus such as in mitochondria and chloroplasts.

What is Gene?

Segment of a chromosome that codes for a particular protein.

What is Hydrogen bonds?

Bonds by which base pairs are linked in DNA.

What is Interphase?

Phase of the cell cycle during which DNA replication occurs.

What is Messenger RNA?

Molecule containing information for protein synthesis in its codons.

What is Transcription?

Transfer of the coded message for protein synthesis from DNA onto mRNA.

What is Transfer RNA?

Molecule containing information for protein synthesis in its anti-codons.

What is Translation?

Part of protein synthesis from the time amino acids are assembled in a particular sequence.

What is Meiosis?

The division of one cell into four cells each of which has half the chromosome number as the parent cell.

What are Homologous Chromosomes?

Chromosomes that are identical in shape and appearance that code for the same set of characteristics.

What is Interphase?

Phase during which DNA replication takes place.

What is Karyotype?

The number and type of chromosomes possessed by an individual.

What is Meiosis?

The type of cell division that results in halving of the chromosome number.

What is Meiosis?

Cell division producing daughter cells that are dissimilar.

What is Metaphase I?

Phase in meiosis in which chromosomes line up at the equator in pairs.

What is Anaphase 1?

Phase in meiosis in which chromosomes are pulled apart.

What is Anaphase II?

Phase in meiosis in which chromatids are pulled apart.

What is Aneuploidy?

The presence of an extra chromosome or absence of one chromosome in gametes due to non-disjunction.

What is Metaphase II?

Phase in meiosis in which chromosomes are arranged singly at the equator.

What is Mitosis?

Cell division producing identical cells.

What is Non-disjunction?

Non separation of chromosomes or chromatids during meiosis.

What is Polyploidy?

The presence of an extra set of chromosomes or the absence of chromosomes in gametes due to non-disjunction.

What is Prophase I?

Phase in meiosis in which crossing-over occurs.

What are Spindle threads?

Structures to which chromosomes are attached during Metaphase I and Metaphase II.

What is the significance of Meiosis?

Leads to the formation of haploid gametes in some organisms and haploid spores in some other organisms.

What are Centrioles?

Structures that form spindle threads during meiosis.

What is a Centrosome?

Structure that splits to form two centrioles in animals cells during meiosis.

What is a Chiasma?

Point of overlap of chromatids during crossing over.

What are Chromatids?

The two strands that make up a chromosome.

What is Crossing over?

The exchange of genetic materials between chromatids of homologous chromosomes.

What is Diploid?

Chromosome condition describing the presence of two sets of chromosomes in each cell.

What is Haploid?

Chromosome condition describing the presence of a single set of chromosomes in each cell.

What is Down syndrome?

Genetic disorder caused by the presence of an extra copy of chromosome 21.

What is Telophase I?

Phase in meiosis in which two cells are formed having half the chromosome complement as the original.

What is Telophase II?

Phase in meiosis in which four cells are formed having half the chromosome complement as the original cell.