Topic 3 Edexcel International AS Level

Complete coverage of the Pearson Edexcel International AS/A Level Specifications topic 3. Learning outcome:

3.1 Know that all living organisms are made of cells, sharing some common features.
3.2 Understand how the cells of multicellular organisms are organised into tissues, tissues into organs and organs into organ systems.
3.3 (i & ii) Know and understand the function of the ultrastructure of eukaryotic cells, including nucleus, nucleolus, ribosomes, rough and smooth endoplasmic reticulum, mitochondria, centrioles, lysosomes and Golgi apparatus.
3.4 Understand the role of the rough endoplasmic reticulum (rER) and the Golgi apparatus in protein transport within cells, including their role in the formation of extracellular enzymes.
3.5 (i) & (ii) Know and understand the function of the ultrastructure of prokaryotic cells, including cell wall, capsule, plasmid, flagellum, pili, ribosomes and circular DNA.
3.6 Be able to recognise the organelles in 3.3 from electron microscope (EM) images.
3.7 (i) Know how magnification and resolution can be achieved using light and electron microscopy.
3.7 (ii) Understand the importance of staining specimens in microscopy
Core Practical 5:
3.8 (i) Use a light microscope to make observations and labeled drawings of suitable animal cells.
3.9 (i) Know that a locus is the location of genes on a chromosome.
3.9 (ii) Understand the linkage of genes on a chromosome.
3.10 Understand the role of meiosis in ensuring genetic variation through the production of non-identical gametes as a consequence of independent assortment of chromosomes in metaphase 1 and crossing over of alleles between chromatids in prophase 1.
3.11 Understand how mammalian gametes are specialised for their functions (including the acrosome in sperm and the zona pellucida in the egg cell).
3.12 Know the process of fertilisation in mammals, including the acrosome reaction, the cortical reaction and the fusion of nuclei.
3.13 Know the process of fertilisation in flowering plants, starting with the growth of a pollen tube and ending with the fusion of nuclei.
3.14 Understand the role of mitosis and the cell cycle in producing genetically identical daughter cells for growth and asexual reproduction.
3.15 Prepare and stain a root tip squash to observe the stages of mitosis.
3.16 Be able to calculate mitotic index.
3.17 (i) Understand what is meant by the terms stem cell, pluripotent and totipotent, morula and blastocyst.
3.17 (ii) be able to discuss the ways in which society uses scientific knowledge to make decisions about the use of stem cells in medical therapies.
3.18 Understand how cells become specialised through differential gene expression, producing active mRNA, leading to the synthesis of proteins which, in turn, control cell processes or determine cell structure in animals and plants.
3.19 Understand how one gene can give rise to more than one protein through post-transcriptional changes to messenger RNA (mRNA).
3.20 (i) Understand how phenotype is the result of an interaction between genotype and the environment.
3.20 (ii) Know how epigenetic modification, including DNA methylation and histone. modification, can alter the activation of certain genes.
3.20 (iii) Understand how epigenetic modifications can be passed on following cell division.
3.21 Understand how some phenotypes are affected by multiple alleles for the same gene, or by polygenic inheritance, as well as the environment, and how polygenic inheritance can give rise to phenotypes that show continuous variation.

Content:

Lesson 1: Observing Cells
History of the microscope and cell theory
Light microscope
Sample staining
Magnification and Resolution
Drawing scientific diagrams
Electron microscopes
Advantages and disadvantages

Lesson 2: Eukaryotic Cells
Recap of GCSEs
Cell organelles
There functions
What the look like under a microscope
Protein transport

Lesson 3: Prokaryotic Cells
All ultrastructures and their functions
Classifying bacteria (including gram staining, shape and oxygen needs)

Lesson 4: Cell Organisation
Types of tissues
Types of epithelial cells
Plant and human organs
GCSE recall of organ systems and their functions

Lesson 5: Cell Cycle and Mitosis.
All steps of the cell cycle
Mitotic Index
Core practical 6

Lesson 6: Sexual Reproduction, Gametes Structure and Function, and Meiosis
Importance of sexual reproduction on variation
Gamete structure, function and location
The steps of meiosis I & II
Variation from recombination and independent assortment

Lesson 7: Fertilisation in Plants and Animals
Internal and external fertilisation
Pollination
Plant fertilisation
Human fertilisation

Lesson 8: Cell Differentiation:
Gene Expression
Cell Differentiation
Effect of Multiple Alleles
Co-dominance
Dihybrid Inheritance
Linked Genes.

Lesson 9: Interaction Between Genes and the Environment:
Environmental effects on Phenotype (Including enzyme activity)
Operons
Studying Variation in Humans.

Lesson 10: Controlling Gene Expression:
Transcription Factors
RNA Splicing
Epigenetics (Including DNA and Histone Methylation, and Histone Acetylation)
Non-Coding RNA

Lesson 11: Stem Cells and Using Stem Cells:
Blastocyst Development
Types of Stems Cells
Where Stem Cells are collected
Epigenetic Control of haemoglobin development
Stem Cell Therapy (including Therapeutic Cloning and iPS Cells)
Examples of potential treatable conditions
Ethics