Genetics is about how information is stored and transmitted between generations.
Introduction
One fundamental property of life is its ability to reproduce. No living thing lives forever. The term of life between birth and death is called an organism's lifespan. In extant organisms, lifespans range from a day (or less) to several centuries.
According to the Cell Theory, cells are the fundamental unit of life. The Cell Theory also states that all cells arise from pre-existing cells. The reproduction of living things occurs at the level of cells. What this means is that no matter whether a living thing is a unicellular or multicellular organism, reproduction is a cellular event. Cellular reproduction is often referred to as cell division (which gives rise to the oxymoronic statement "cells multiply by division"!). In all biological systems studied thus far, the genetic information in cells must be reproduced before cell division occurs. In some types of reproduction, the goal is to ensure that the genetic information of the parental generation is faithfully reproduced in the next generation; in other situations, the genetic information is slightly altered between generations.
Therefore, heredity (the passing of biological traits from one generation to the next) is closely linked to the mechanisms of reproduction. But not always. Biologists have identified two different modes of heredity.
Heredity that involves reproduction (parent-to-offspring; intergenerational) vertical gene transfer.
Heredity that does not involve reproduction (organism-to-organism) is referred to as horizontal gene transfer.
Figure 1: A comparison of vertical and horizontal gene transfer. Image by Gregorius Pilosus. This file is licensed under the Creative CommonsAttribution-Share Alike 3.0 Unported license.
Inquiry questions
The content of this module is organised around the following inquiry questions:
How does reproduction ensure the continuity of a species?
How important is it for genetic material to be replicated exactly?
Why is polypeptide synthesis important?
How can the genetic similarities and differences within and between species be compared?
Can population genetic patterns be predicted with any accuracy?
Links to other areas of the syllabus
To develop a deep understanding of the concepts in this module, you should revise the following areas from the Year 11 Biology course, paying attention to the organisation of genetic information in cells, and Evolutionary Theory from a molecular perspective:
Inquiry question: What distinguishes one cell from another?
Students investigate different cellular structures, including but not limited to, examining a variety of prokaryotic and eukaryotic cells
Students investigate a variety of prokaryotic and eukaryotic cell structures, including but not limited to, comparing and contrasting different cell organelles and arrangements
Inquiry question: What is the relationship between evolution and biodiversity?
Students explain modern-day examples that demonstrate evolutionary change, for example, antibiotic-resistant strains of bacteria
Students explain, using examples, how Darwin and Wallace’s Theory of Evolution by Natural Selection accounts for:
convergent evolution
divergent evolution
Inquiry question: What is the evidence that supports the Theory of Evolution by Natural Selection?
Students investigate, using secondary sources, evidence in support of Darwin and Wallace’s Theory of Evolution by Natural Selection, including but not limited to, biochemical evidence, comparative anatomy, comparative embryology and biogeography