Inheritance, Genes & Cell Division, Biotechnology & Genetic Modification, Energy & Feeding Relationships

What is inheritance?

The transmission of genetic information from generation to generation

Where are chromosomes found?

In the nucleus of cells

What are chromosomes?

Thread like structures made of DNA carrying genes

What is a gene?

A short length of DNA that codes for a specific protein

What do genes control?

Characteristics by controlling protein production

What are alleles?

Different versions of the same gene

How many alleles does an individual have for each gene?

Two

Where do alleles come from?

One from the mother and one from the father

Define genotype

The combination of alleles an organism has

Define phenotype

The observable characteristics of an organism

What is a dominant allele?

An allele that shows with only one copy

What is a recessive allele?

An allele that only shows with two copies

Define homozygous

Having two identical alleles

Define heterozygous

Having two different alleles

What letters are used for alleles in genetic diagrams?

Capital for dominant lowercase for recessive

What determines sex in humans?

Sex chromosomes

What sex chromosomes do females have?

XX

What sex chromosomes do males have?

XY

Who determines the sex of the baby?

The father

Why does the father determine sex?

He provides X or Y sperm

What is protein synthesis?

The production of proteins from DNA instructions

What are the two stages of protein synthesis?

Transcription and translation

Where does transcription occur?

In the nucleus

What is transcription?

Copying DNA code into mRNA

Why can DNA not leave the nucleus?

It is too large

What is mRNA?

Messenger RNA that carries the code to ribosomes

Where does translation occur?

At ribosomes

What is translation?

Using mRNA to build amino acids into proteins

What is a triplet code?

Three bases coding for one amino acid

What controls amino acid sequence?

Base sequence of DNA

What is gene expression?

Whether a gene is switched on or off

Why are many genes switched off?

To save energy and resources

What are haploid cells?

Cells with one set of chromosomes

What are diploid cells?

Cells with two sets of chromosomes

How many chromosomes are in human body cells?

46

How many chromosomes are in human gametes?

23

What is mitosis?

Nuclear division producing identical cells

State three functions of mitosis

Growth repair asexual reproduction

Are cells produced by mitosis haploid or diploid?

Diploid

Are daughter cells genetically identical in mitosis?

Yes

What are stem cells?

Unspecialised cells that can divide and differentiate

What is the ultimate stem cell?

The zygote

What is meiosis?

Nuclear division producing genetically different cells

Why does meiosis occur?

To produce gametes

What type of cells does meiosis produce?

Haploid cells

How many cells are produced in meiosis?

Four

How many divisions occur in meiosis?

Two

Why does meiosis increase variation?

Recombination and random fertilisation

Give two differences between mitosis and meiosis

Mitosis produces identical cells meiosis produces variation

What is monohybrid inheritance?

Inheritance of one gene

What is a Punnett square?

A diagram showing possible allele combinations

What ratio is produced from heterozygous crosses?

3 to 1

What is codominance?

Both alleles affect the phenotype

Give an example of codominance

Blood groups

What alleles control blood groups?

IA IB and IO

Which alleles are codominant?

IA and IB

What is a sex linked characteristic?

A trait controlled by a gene on the X chromosome

Why are males more affected by sex linked disorders?

They have only one X chromosome

What is a carrier?

A female with one recessive allele

Give two examples of sex linked disorders

Haemophilia colour blindness

What is biotechnology?

Using organisms to make useful products

Why are bacteria useful in biotechnology?

They reproduce rapidly and make complex molecules

What are plasmids?

Small circular DNA in bacteria

Why are plasmids useful?

They transfer genes easily

What is fermentation?

Anaerobic respiration by microorganisms

What does yeast produce during fermentation?

Ethanol and carbon dioxide

How is yeast used in bread making?

Carbon dioxide makes dough rise

How is yeast used in biofuel production?

Ethanol is used as fuel

What enzyme is used in fruit juice production?

Pectinase

What does pectinase do?

Breaks down pectin in cell walls

Why do biological detergents contain enzymes?

To break down stains

Give two advantages of biological detergents

Lower temperatures and faster cleaning

What is lactose?

Sugar found in milk

What enzyme digests lactose?

Lactase

How is lactose free milk produced?

Adding lactase enzyme

What is penicillin?

An antibiotic

Who discovered penicillin?

Alexander Fleming

What produces penicillin?

Penicillium mould

What is an industrial fermenter?

A vessel for growing microorganisms

Why are fermenters kept aseptic?

To prevent contamination

Why is temperature controlled in fermenters?

To maintain optimum enzyme activity

What is genetic modification?

Changing genetic material by inserting genes

What is a transgenic organism?

An organism with genes from another species

What is recombinant DNA?

DNA containing genes from different organisms

Give an example of GM bacteria

Insulin producing bacteria

What enzyme cuts DNA?

Restriction enzymes

What enzyme joins DNA?

DNA ligase

Why are bacteria used for genetic engineering?

They share the same genetic code

What is a GM crop?

A crop with altered genes

Give one advantage of GM crops

Increased yield or pest resistance

What is the main source of energy for ecosystems?

The Sun

How does energy enter food chains?

Photosynthesis

What is a food chain?

A sequence showing energy transfer

What do arrows in food chains represent?

Energy transfer

What is a producer?

An organism that makes its own food

What is a consumer?

An organism that eats others

What is a food web?

Interconnected food chains

What does interdependence mean?

Species depend on each other

What is a pyramid of numbers?

Diagram showing number of organisms

Why can pyramids of numbers be inverted?

Large producers support many consumers