Unit Two:The Cell

Suggested Time Allowance in Class Periods:

2.1 CELL STRUCTURE

2.1.1 Microscopy

2.1.2 Cell Structure and Function

2.1.3 Cell Ultrastructure

H.2.1.4 Prokaryotic and Eukaryotic Cells

An introduction to the microscope. Specific reference to the light microscope and the transmission electron microscope.

Components of the cell as seen under the light microscope and their functions.

Plant cells: cell wall, cytoplasm, nucleus, vacuole, and chloroplast. Animal cells: cytoplasm and nucleus.

In both cases indicate the position and function of the cell membrane.

Identification and function of the cell membrane, mitochondrion, chloroplast, nucleus, nuclear pores, ribosome, and DNA.

Existence and definition of "prokaryotic" and "eukaryotic" cells.

Be familiar with and use the light microscope.

Prepare and examine one animal cell and one plant cell (e.g. own cheek cells, onion cells, Elodea leaf, potato tissue and moss) unstained and stained using the light microscope (x100, x400).

2.2 CELL METABOLISM

2.2.1 Cell Metabolism

2.2.2 Sources of Energy

2.2.3 Enzymes

2.2.4 Photosynthesis

2.2.5 Respiration

2.2.6 Movement through Cell Membranes

H.2.2.7 Enzymes (Extended Study)

H.2.2.8 Role of Adenosine Triphosphate (ATP) and Nicotinamide Adenine Dinucleotide (NAD)

H.2.2.9 Photosynthesis (Extended Study)

H.2.2.10 Respiration (Extended Study)

Definition of "metabolism".

Reference to solar energy and cellular energy.

Definition of "enzymes"­reference to their protein nature, folded shape, and roles in plants and animals. Special reference to their role in metabolism.

Effect of pH and temperature on enzyme activity.

Definition and role of "photosynthesis". Representation by a balanced equation of the overall sequence of reactions.

A simple treatment of photosynthesis. Chlorophyll in chloroplasts traps sunlight energy. This trapped energy splits water to release electrons, protons, and oxygen. These electrons are passed to chlorophyll, the protons are released to a general pool of protons. The oxygen is either released to the atmosphere or used within the cell.

Electrons from chlorophyll are used with protons from the pool of protons and carbon dioxide to form a carbohydrate Cx(H2O)y.

Location of chlorophyll within cells.

Identification of the source of light, carbon dioxide and water for photosynthesis in leaf cells.

Describe the application of high salt or sugar concentration in food preservation.

Definition and role of "aerobic respiration". Representation by a balanced equation of the overall sequence of reactions for glucose.

A simple treatment of aerobic respiration of glucose by reference to a two-stage process. Stage 1 does not require oxygen and releases a small amount of energy. Stage 2 does require oxygen and releases a large amount of energy.

Definition of "anaerobic respiration". Reference to fermentation.

Cellular location of the first and secondstage process.

Selective permeability of membranes surrounding the cells and within the cells.

Definition of the terms "diffusion" and "osmosis". Examples of each.

Definition of "turgor". Simple explanation of turgidity in plant cells.

The Active Site Theory to explain enzyme function and "specificity".

Explanation of the term "optimum activity" under specific conditions as applied to pH range.

Heat denaturation of protein.

Nature and role of ATP, production of ATP from ADP + P + Energy.

Role of NADP+ in trapping and transferring electrons and hydrogen ions in cell activities.

Photosynthesis as a two-stage process. The first stage, driven by light energy, is called the light stage or light-dependent stage. The second stage, which is dependent on the products of the light stage and does not require light, is called the dark stage or light-independent stage.

In the light stage refer to the transfer of energy, the production of energised electrons, and their subsequent two-pathway systems.

Pathway 1: by direct return to chlorophyll and the formation of ATP.

Pathway 2: trapped by the reduction of NADP+ to NADP­; photolysis of water producing protons and electrons and releasing oxygen. H+ is attracted to NADP­ to form NADPH.

In the dark stage, protons and electrons are transferred from NADPH to CO2 in the production of Cx(H2O)y. Role of ATP. Regeneration of ADP and NADP+ to the light stage.

(Further biochemical references not required).

First-stage process: Glycolysis ­ the conversion of a six-carbon carbohydrate to pyruvate with the generation of ATP.

Fermentation option ­ ethanol or lactic acid production.

Second-stage process: Production of Acetyl Co. A and one molecule of carbon dioxide. Krebs Cycle and the electron transport system, which produce more carbon dioxide, water, and ATP molecules.

(Further biochemical references not required).

Bioprocessing with immobilised enzymes ­ procedure, advantages, and use in bioreactors.

Human intervention: use of artificial light and carbon dioxide enrichment to promote crop growth in greenhouses.

Examine the role of microorganisms in industrial fermentation, including bioprocessing with immobilised cells: procedure, advantages, and use in bioreactors.

Describe the application of high salt or sugar concentration in food preservation.

Investigate the effect of pH on the rate of one of the following: amylase, pepsin or catalase activity.

Investigate the effect of temperature on the rate of one of the following: amylase, pepsin or catalase activity.

Prepare one enzyme immobilisation and examine its application.

Investigate the influence of light intensity or carbon dioxide on the rate of photosynthesis.

Prepare and show the production of alcohol by yeast.

Conduct any activity to demonstrate osmosis.

Investigate the effect of heat denaturation on the activity of one enzyme.

2.3 CELL CONTINUITY

2.3.1 Cell Continuity and Chromosome

2.3.2 Haploid, Diploid

2.3.3 The Cell Cycle

2.3.4 Mitosis

2.3.5 Function of Mitosis

2.3.6 Meiosis

2.3.7 Functions of Meiosis

H.2.3.8 Stages of Mitosis (Extended Study)

Explanation of the terms "cell continuity" and "chromosome".

Definition of "haploid" and "diploid" number.

Description of cell activities in the state of non-division (interphase) and division (mitosis).

Definition of "mitosis". Simple treatment, with the aid of diagrams. (Names of stages and of chromosome parts are not required).

Primary function in single-celled and multicellular organisms.

Definition of "meiosis".

Functions of "meiosis".

Detailed study, with the aid of diagrams, of the stages of mitosis

2.4 CELL DIVERSITY

2.4.1 Tissues

2.4.2 Organs

2.4.3 Organ System

Definition of a "tissue". Exemplify by using four tissue types, two each from a plant and an animal.

Definition of an "organ". Exemplify by using two kinds of organs, one each from a plant and an animal.

Definition of an "organ system". Exemplify by using any two animal organ systems

2.5 GENETICS

2.5.1 Variation of Species

2.5.2 Heredity and Gene Expression

2.5.3 Genetic Code

2.5.4 DNA Structure, Replication and Profiling

2.5.5 Protein Synthesis

2.5.6 Genetic Inheritance

2.5.7 Causes of Variation

2.5.8 Evolution

2.5.9 Genetic Engineering

H.2.5.10 Origin of the Science of Genetics

H.2.5.11 Law of Segregation

H.2.5.12 Law of Independent Assortment

H.2.5.13 Dihybrid Cross

H.2.5.14 Nucleic Acid Structure and Function (Extended Study)

H.2.5.15 Protein Synthesis (Extended Study)

Knowledge of the diversity of organisms. Definition of "species".

Definition and example of "heredity" and "gene expression".

Definition and role of a "gene".

Chromosome structure.

Simple structure of DNA: two strands with Adenine(A)­Thymine(T), Guanine(G)­Cytosine(C) complement.

Coding and non-coding structures.

RNA as a complementary structure to DNA. Reference to uracil. Knowledge of the function of messenger RNA (mRNA).

Replication of DNA involving the opening of the helix followed by the synthesis of complementary nucleic acid chains alongside the existing chains to form two identical helices.

Protein synthesis as follows:

• DNA contains the code for protein
• this code is transcribed to mRNA
• the transcribed code goes to a ribosome
• the code is translated and the amino acids are assembled in the correct sequence to synthesise the protein
• the protein folds into its functional shape.

Gamete formation. Definition of a "gamete" and its function in sexual reproduction in plants and animals.

Definition of the following terms:

• fertilisation
• allele
• homozygous and heterozygous
• genotype
• phenotype
• dominance
• recessive
• incomplete dominance.

Study of the inheritance to the first filial (F1) generation of a single unlinked trait in a cross involving:

• homozygous parents
• heterozygous parents
• sex determination.

The genotypes of parents, gametes and offspring should be shown.

Variation from: sexual reproduction and mutations.

Definition of "evolution". Theory of Natural Selection. Evidence from any one source.

Manipulation and alteration of genes. Process involving isolation, transformation, and expression.

Work of Gregor Mendel leading to the expression of his findings in two laws.

State and explain the Law of Segregation.

State and explain the Law of Independent Assortment.

Study of the inheritance to the second filial generation (F2) of two unlinked traits using the Punnett square technique.

Definition of linkage. Explanation of change in 1:1:1:1 probability for a dihybrid heterozygote crossed with a dihybrid recessive organism. (Knowledge of crossing over is not required).

Sex linkage.

Non-nuclear inheritance, e.g. mitochondrial and chloroplast DNA.

DNA structure, to include: deoxyribose sugar, phosphate, and four named nitrogenous bases. Specific purine and pyrimidine couples ­ complementary base pairs. Hydrogen bonding. Double helix.

Location of protein synthesis, process of protein synthesis ­ reference only to molecular involvement of DNA, mRNA, tRNA, rRNA and amino acids to provide an understanding of their role in coding information.

DNA profiling: definition, any two applications. Stages involved:

• cells are broken down to release DNA
• DNA strands are cut into fragments using enzymes
• fragments are separated on the basis of size
• the pattern of fragment distribution is analysed.

Genetic screening: screening test diagnosis because of changed genes. (Detail of process not required).

Two agents responsible for increased mutation rates.

Three applications: one plant, one animal, one micro-organism.