Yr 12 Biology Mid-Year Exam Notes Part 2

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Macromolecules

M6: Polysaccharides and Lipids are important macromolecules in cells and organisms

Learning Objective

Polysaccharides, including cellulose and chitin and Lipids contribute to the structural components of cells and organisms

Polysaccharides, including, starch and glycogen and Lipids including, fats and oil contribute to energy reserves in cells

Macromolecules Overview

Types of Compounds Elements Contained Unit Names - Large/Small Where Found/Use

Carbohydrates C, H, O - Monosaccharides = Glucose

(polysaccharides) - Disaccharides = Sucrose

- Polysaccharides = Starch, Glycogen,

Cellulose, Chitin

Lipids C, H, O (P) - Lipids (Triglycerides) = made of Glycerol

and Fatty acids (fats and oils)

- Phospholipids = made of two Fatty acids

attached to a Glycerol, a Phosphate and

Ethanolamine

- Hormone Lipid Derivatives = Steroids and

Waxes

Proteins C, H, O, N (S) Amino acids combine (20 types) to make

polypeptides which can be either;

- Structural = Collagen

- Functional = Enzymes

Nucleic Acids C, H, O, N - DNA = Chromosomes, Genes, Nucleotides,

Nitrogen Base, Sugar and Phosphate

PLANTS

ANIMALS

CELLULOSE

STARCH

CHITIN

GLYCOGEN

STRUCTURE

Long straight chains of glucose

molecules. This tough fibrous molecule

is unable to be broken down for use by organisms, including humans

Long branched chains of glucose

molecules.

Chains of glucose with added N

groups. It forms a hard protective

covering.

Long branched (more than starch)

chains of glucose molecules.

Polysaccharides stored as Glycogen

in animals found mainly in liver and muscle tissue.

FUNCTION

Principle component of CELL WALLS. Provides strength to plant cells.

Storage of glucose units until

needed in plants. A plant can store

reserves of starch that can be easily broken down into glucose for use in

cellular respiration.

Found in the exoskeleton of

organisms such as; spiders, insects and crustaceans. Also found in cell walls

of fungi

Storage of glucose units until

needed in animals, (liver/muscles).

Glycogen can be broken down to increase blood glucose as the demand

for energy increases.

Link S/F

Straight chains gives strength to

cell wall by H bonds

Insoluble and branching makes it

an efficient molecule to store glucose

N groups aid formation of H bonds

across chains hence adds to strength

Readily accessible, branching

makes it an efficient molecule to store glucose. Glycogen is insoluble and thus easily

stored in vacuoles and granules for rapid use by the cell.

CONTRIBUTE

TO STRUCTURAL COMPONENTS

ENERGY

RESERVES

CONTRIBUTE

TO STRUCTURAL COMPONENTS

ENERGY

RESERVES

Polysaccharides = STRUCTURE & ENERGY

Lipids = STRUCTURE & ENERGY

PHOSPHOLIPIDS

LIPIDS (Fats & oils)

WAXES

STEROIDS

STRUCTURE

Triglyceride with FA removed

and phosphate added. When in water these molecules tend to

organise themselves in rows

•Triglyceride

containing glycerol and three fatty acids.

•Lipids

are solid at room temp =fats.

•Lipids

that are liquid at room temp = Oils.

•

Fatty tissue (Adipose tissue) consists of only a small cytoplasm surrounded by fat globules.

Produced by both

Plants and Animals, often acting as a protective layer.

Steroids are

hormones that are produced from lipids (cholesterol) and therefore are known

as lipid derivatives.

FUNCTION

To create a

semi-permeable barrier to

cellular molecular movement

Insulation, energy storage.

Many animals(whales, seals,

dolphins) have a layer

of fat under the skin and around vital organs to insulate from the cold and as an energy store.

Oils tend to be found in plants where they act as energy stores. Olive oil, sunflower oil

PLANTS

A waxy cuticle can

be found on the leaves of some plants to prevent water loss.

ANIMALS

Some insects have

a waxy cuticle to prevent water loss.

Humans and some other animals produce wax in the ears to stop dust and

prevent water penetrating the ear drum.

Cholesterol is a

component of animal cell membranes but NOT plant cell membranes. It is an important precursor

molecule for the production of other steroids.

Link S/F

Hydrophobic / hydrophilic

nature of the molecule

Long fatty acids chains are

energy rich

Hydrophobic

molecule

A type of lipid

that includes some hormones and cholesterol

CONTRIBUTE

TO STRUCTURAL COMPONENTS

ENERGY

RESERVES

CONTRIBUTE

TO STRUCTURAL COMPONENTS

CONTRIBUTE

TO STRUCTURAL COMPONENTS

M1: The chemical unit of genetic information in most organisms is DNA

Learning Objective

Model the structure of SNA as a double helix made up of a sequence of complementary bases joined by weak bonds attached to a background of alternating sugars and phosphates

Describe the component parts of a nucleotide

Understand that DNA is composed of a sequence of nucleotides

Write the complementary sequence for a segment of DNA

Inherited Characteristics

Chromosomes carry the genetic information for making all living things - everything from a human to a gerbil!

What makes us human? What determines our gender?

In all living things, characteristics are passed on in the chromosomes that offspring inherit from their parents

So all human characteristics, including gender, are based on which chromosomes we inherit

What are chromosomes?

Chromosomes are long strands of genetic information located in the nuclei of cells

Chromosomes are most visible during cell division when they replicate and look like this

Homologous Chromosomes

In most cells chromosomes are matched in pairs based on their size and shape

Chromosome from female parent

Chromosome from male parent

Homologous chromsomes

Matching pairs of chromosomes are called homologous chromosomes

Each pair of homologous chromosomes contains one chromosome that has been inherited from each parent

The Human Karyotype

DOUBLE

HELIX

SHAPE

The Human Genome Project

The Human Genome Project commenced in 1988

Its aim was to map the 40 000 genes (entire human genome) of one woman and one man

It was completed in 2000, 3 years ahead of schedule

It will take another 100 years to analyse the data collected

The WCH was responsible for sequencing the DNA on chromosome 16

Benefits

Cells differentiation

Embryo development

Evolution

New diagnosis

Disease prevention

Treatment

What is DNA?

Chromosomes and their genes are made of a molecule called DNA

DNA stands for Deoxyribose nucleic acid

Each chromosome isa very long molecule of tightly coiled DNA

DNA molecules carry the code that controls what your cells are made of and what they do

Chromatin to Chromosomes

Super-coiled structure wrapped around proteins called histones

Combination of DNA and histones called chromatin

Just before cell division this chromatin condenses into short fat structures called chromosomes

All cell division consists of two identical chromatids

Structure of SNA

DNA is found in the nucleus

It is made up of repeating units called nucleotides

Each nucleotide is made up of 3 molecules

A base (A, T, G, C)

A sugar (deoxyribose)

A phosphate

M6

M1