Summary
Summary Life Sciences Grade 12 Term 01 (Focus textbook)
- Course
- Life Sciences
- Institution
- 12th Grade
Summary of 23 pages for the course Life Sciences at 12th Grade (.)
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0, Table of contents
Topic 1 : DNA (The code of life) .................................................................................................... 2
Unit 1 : Deoxyribonucleic acid (DNA) ........................................................................................... 2
Unit 2 : Ribonucleic acid (RNA) .................................................................................................... 6
Topic 2 : Meiosis ............................................................................................................................ 8
Unit 1 : Meiosis ............................................................................................................................. 8
Unit 2 : Consequences of abnormal meiosis .............................................................................. 11
Unit 3 : Mitosis and meiosis ........................................................................................................ 12
Topic 3 : Reproduction in vertebrates ....................................................................................... 13
Unit 1 : Diversity of reproductive strategies in vertebrates ......................................................... 13
Topic 4 : Human reproduction .................................................................................................... 16
Unit 1 : Structure of male and female reproductive systems ...................................................... 16
Unit 2 : Unique human characteristics of some aspects of reproduction .................................... 19
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, Topic 1 : DNA (The code of life)
UNIT 1 : DEOXYRIBONUCLEIC ACID (DNA)
Glossary
Term Definition
Short for deoxyribonucleic acid, it contains the instructions used in the
DNA
development and functioning of almost all known living orgnisms.
Long strands, made of DNA and proteins in the nucleus of a cell, which
Chromosomes
contain genetic information.
Histones Proteins that form part of the chromosomes.
A section or chemical structure of DNA in a chromosome, which carries a
Gene
code about a particular characteristic in an organism.
Extranuclear DNA DNA found outside of the nucleus.
Double helix The structure of DNA, which forms a spiral ladder-shaped molecule.
The building blocks of DNA, which consist of a nitrogen-containing purine
Nucleotides
or pyrimidine base linked to a sugar and phosphate group.
DNA: location in the cell
• DNA is primarily located in the nucleus of a cell and is part of the
chromosome structure.
• Chromosomes are long strands made of DNA and proteins in the nucleus of
a cell.
• Genetic information is contained within chromosomes in the nucleus of a
cell.
• Chromosomes are formed from DNA and proteins called histones.
• DNA is tightly wound around the histones.
DNA: chromosomes and genes
• During non-dividing phases, chromosomes in a cell become long and thin.
• Genes are sections of DNA along each chromosome.
• Genes provide instructions for the structure and function of cells and specific traits.
• Eye color is an example of a characteristic controlled by a group of genes.
• DNA carries the code or instructions for genes.
Extranuclear DNA
• DNA is primarily located in the nucleus of a cell, but other organelles also contain DNA.
• Mitochondria in plant and animal cells, as well as chloroplasts in plant cells, have DNA.
• DNA outside the nucleus is known as extranuclear DNA.
• DNA in mitochondria is called mitochondrial DNA (mtDNA).
• mtDNA is passed down maternally from generation to generation.
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