Unit 1: Chapter 6 - Variation, Production and New Technology

Question 1

Inheritance

Answer 1

WHY DO WE LOOK LIKE OUR PARENTS?

We have similar characteristics to our parents due to genetic information in our sex cells called GAMETES. The genetic information will determine what you will look like.

CHROMOSOMES

The genetic information is held within the NUCLEUS. The genetic information is passed down through generations during reproduction.

Within the nucleus, there are CHROMOSOMES and these are made up of a special chemical called deoxyribonucleic acid (DNA) This is exactly where genetic information is stored.

WHAT DOES DNA LOOK LIKE?

DNA is a long molecule make up of two strands to make a spiral. This is known as the DOUBLE HELIX. This can be a similar representation to a twisted ladder
CHROMOSOMES IN DETAIL

Each living organism has a different number of chromosomes in their body cells. Humans have 46 chromosomes - 23 each from your mother and father. There are 23 pairs altogether.

Within these chromosomes there are thousands of genes, which determine what the organism is like. This includes size, colour and shape.

Your chromosomes are organised so that in a pair, they carry genes controlling the same thing.

Some of your characteristics are decided by a single pair of genes, for example there is one pair of genes that determines whether or not you will have dimples. However, most of your characteristics are the result of several different genes working together.

Question 2

Types of Reproduction

Answer 2

There are two types of reproduction:

• Sexual reproduction
• Asexual reproduction

ASEXUAL REPRODUCTION

Asexual reproduction involves only one parent.

Asexual reproduction gives identical offspring known as CLONES.

Very common in SMALL ANIMALS, PLANTS and

SEXUAL REPRODUCTION

Sexual reproduction involves both a male sex cell and a female sex cell. These forms together to form a new individual.

From sexual reproduction, the offspring will inherit genetic information from both parents so there will be variation.

In plants, reproduction is found within ovules and pollen.

VARIATION

Variety gives the advantage to ensure that a species survive. Variety makes it more like for the species to survive in difficult conditions and survive a deadly disease.

Question 3

Genetic and Environmental Differences

Answer 3

GENETIC VARIETY

Genetic information determines your characteristics. Your genes are only part of the story and environmental factors also determine what you look like.

ENVIRONMENTAL FACTORS

Examples of environmental factors are when:

• A pregnant woman drinks heavily and the result of the new-born baby will be very small and have learning difficulties.
• Scars from accidents are also environmental
• Genetically-identical plants will look different under different conditions (CO2, light and nutrients)

COMBINATION OF GENETIC AND ENVIRONMENTAL FACTORS

One example could be your skin colour. It may be originally lighter in colour, but living in sunny conditions will make your skin darker.

Question 4

Cloning

Answer 4

CLONING PLANTS

There are two methods of cloning plants:

• Cuttings - If you cut a piece of plant off and grow it in the correct conditions, new roots will form. It will give a single, new plant. Using hormones will increase the chance the cutting will develop into a plant.
• Tissue Culture - It’s more expensive, however it allows you to make thousands of new plants from a piece of tissue. Hormones are used to stimulate plant cells and placed under the correct conditions, it can produce thousands of the desired plant.

Question 5

Cloning - Part 2

Answer 5

ANIMAL CLONING (EMBRYO CLONING)

For cows, you use cow-fertility hormones so that you can extract plenty of eggs. You then fertilise these eggs from a desired bull’s sperm.

An embryo is a cluster of unspecialised cells. The embryo is then divided into individual cells and then waited until they develop into embryos. Each embryo is then transferred into a cow, which then produce genetically-identical cattle.

ADULT CELL CLONING

• The nucleus is removed from an UNFERTILISED EGG CELL.
• A nucleus is removed from an adult body cell. e.g. skin cell of the same species.
• The nucleus of the adult cell is then placed in the empty egg cell.
• When the egg cell is developed into an embryo, it is then placed into the womb of an adult female.

+ Larger numbers of more useful animals.
+ Save animals from extinction
- People are unhappy about bringing prized animals back.
- May lead to human cloning
- Population is less likely to survive from disease or change in environment.

Question 6

Genetic Engineering

Answer 6

Genetic engineering is the extraction of a particular gene and transfer it to the genetic material of a completely different organism. This method can also be used to farm the exact proteins we need e.g. human insulin.

• Extract human gene in its own DNA with restrictive enzymes
• Take the plasmid out of a bacterium and split with restrictive enzymes.
• Insert insulin gene in plasmid with restrictive enzymes
• Modified plasmid is then taken up by bacterium which can then be easily farmed as it reproduces quickly. The bacteria must reproduce in its optimum conditions to farm its fastest.

ADVANTAGES
+ Can make the exact proteins we need
+ improve growth rate of plants and animals
+ crops can be engineered to make there own herbcides and pesticides.

DISADVANTAGES

• No idea what long-term effects are
• Farmers in poor countries are at disadvantages because they have tp buy seeds every year. This is because GM seeds are infertile.
• People may want to manipulate genes are their babies.