Four Groups of Macromolecules:

Fourth Macromolecule Group: Nucleic Acids

There are two types of nucleic acid 1.DNA 2.RNA

1. DNA: deoxyribonucleic acid The genetic information of a cell Located in the nucleus Works with RNA to regulate the primary structure of amino acids in proteins

Made of 4 nucleotides: adenine, thymine, cytosine, guanine

In DNA, the central sugar is a deoxyribose, in RNA a ribose

- Nucleotides in a single strand of nucleic acid join together through a phosphodiester bond

-In a DNA molecule, one strand joins together with another strand of nucleotides through hydrogen bonds

Adenine forms 2 hydrogen bonds with Thymine –A is complementary to T Cytosine forms 3 hydrogen bonds with Guanine –C is complementary to G

When a cell needs a specific protein it sends a signal to the nucleus, telling it to make that protein The nucleus makes a “photocopy” of the piece of DNA that carries the information for the desired protein: mRNA

2. RNA: ribonucleic acid RNA is a nucleic acid where the central sugar of each nucleotide is a ribose

RNA has 4 nucleotides, with Thymine being replaced by Uracil A binds to U C binds to G

RNA can travel from the nucleus to the cytoplasm of the cell (the area outside the nucleus) The machinery for making proteins (ribosomes) is outside of the cell nucleus

Translation: in the cytoplasm RNA is “translated” into an amino acid sequence by ribosomes

Central Dogma of Molecular Biology DNA  RNA  protein

because we have A LOT of DNA in each cell it needs to be packaged in a specific way, into chromosomes

Homework 1.Complete the following table: Macromoleculeexamplesstructurefunctions Carbohydrates Lipids Proteins Nucleic acids

2. Compare DNA and RNA. What is the function of each? Where is each located in a cell? 3. Why is genetic material crucial to the well-being of a cell

CANCER - a closer look at the nucleus and its role in the cell

Cancer in Canada

Cancer Risk Factors There are many known risk factors for cancer: Tobacco Use almost 30% of all fatal cancers in Canada major cause of lung cancer Poor Diet one with a high proportion of dietary fat, about 20% of fatal cancers Colon and prostate cancers are associated with diets high in fat

Other Risks workplace hazards family history alcohol use reproductive factors sexual activity sunlight/ ionizing radiation drugs

But…What’s causing cancer? A look inside the nucleus

Multi cellular organisms = billions of cells cells need to divide and copy themselves for a variety of reasons. For example: –cells wear out and need to be replaced –new cells allow the body to repair damaged tissue –new cells allow the body to grow (cells themselves don't grow beyond a certain size).

Cell Division -The most common form of cell division is mitosis -Occurs in all body cells and is used for growth and repair -cell makes an exact copy of itself and splits into two new cells -Each cell contains an exact copy of the original cell’s DNA: this is the reason why all the cells in an organism are genetically identical

Cell division occurs through a copying of its genetic information

At the end of mitosis you end up with two identical (daughter) cells, each carrying the same DNA

But…what’s so important about DNA? In a cell all functions are carried out by proteins: control of cell reproduction, production of energy, production of hormones, production of digestive enzymes, etc. DNA contains genes: the blueprints for those proteins Each gene is an assembly guide (think IKEA) on how to put the protein together

DNA  RNA  protein

If there is a mistake (mutation) in the blueprint, in the DNA, there will be a mistake in the protein Most times the cell will detect the mistake and die:

Figure 9.21 Apoptosis: Programmed Cell Death

When cell division goes wrong Cell division is tightly controlled by genes inside the nucleus. Special genes, called oncogenes, stimulate cell division If through a mutation an oncogene is irreversibly switched “on” it can cause uncontrolled cell division

CANCER = uncontrolled cell division Cells divide, divide, and divide…

tumour

The uncontrolled growth of cells forms a lump called a tumour. –Some tumours are benign and may not cause any problems. –Others are malignant. They can invade into other body tissues and cause severe damage. It is these malignant tumours that we call cancer. There are over 200 different types of cancer and they can occur anywhere in the body.

Cancer Treatments 1.Surgery - Effective for tumours in a defined area, often the first treatment 1.Chemotherapy -Medication used to target and kill quickly-dividing cancer cells: some prevent new cells from splitting apart, while others stop the production of new DNA 2.Radiation therapy - high-energy radiation is aimed at the growing tumour to damage its DNA 3.Some combination

Cancer Treatments 1. Surgery Often the first treatment is to surgically remove the malignant tumour to stop it growing and spreading further. This is most effective against tumours that are in a defined area, ex. breast, ovary, testicular cancers. 2. Chemotherapy Medicines have been developed that can treat both primary and secondary tumours. They target fast-growing cells to stop mitosis. Some prevent the new cells splitting apart whilst others stop the production of new DNA. 3. Radiotherapy High energy gamma radiation is aimed at the growing tumour. This damages the DNA in rapidly dividing cells and so helps to destroy the tumour.

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