B6- Inheritance, variation and Evolution

What does DNA stand for

deoxyribonucleic acid

What is a chromosome

Long structure of DNA which usually comes in pairs

What is a gene

A small section of DNA found on a chromosome which codes for a particular sequence of amino acids

What is a Genome

An entire set of genetic material in an organism

Why is researching the human genome important?

* allows scientists to identify genes in the genome that are linked to different types of disease
* Knowing which genes are linked to inherited disease to help treat them
* Can help to trace migration of certain populations and identify when theses populations split off from each other a developed different characteristics

What is sexual reproduction?

Where genetic info from two organisms (male and female) combine to produce offspring which are genetically different to either parent.

What combines to create an embryo in sexual reproduction

Male (sperm) and female (eggs) gametes

How many chromosomes does a normal cell contain

46 (23 from each gamete)

What is term for the fusion between mother and father gametes

fertilisation

What is the term for a mixture of genetic information

Variation

What plants also reproduce sexually

Flowering plants which contain egg cells but have pollen instead of sperm

What is asexual reproduction

reproduction involving only one parent meaning the offspring are genetically identical and occurs through mitosis only

Is offspring similar to its parent if they are produced from asexual reproduction

Yes they are clones of their parent

What produces offspring are reproduced asexually

Bacteria, some plants and some animals

What is meiosis

In order to ensure gametes only have one copy of each chromosome so that gamete fusion takes place with the right amount of chromosomes at the end. In humans this only occurs in the reproductive organs.

how many cell divisions occur in meiosis

2

In sexual reproduction how do the cells grow after gamete fusion

Mitosis

How can you find the probability of genetic outcomes e.g. whether you are going to have a boy or a girl

Genetic diagrams

What controls you’re characteristics

Genes inherited from parents

What are different versions of genes

alleles

What is the term for having two of the same alleles

homozygous

What is the term for having two different alleles for a gene

heterozygous meaning there is recessive and dominant gene

How can an organism display a recessive characteristic

if both allele are recessive

What is a genotype

The combination of alleles you have

What is Cystic Fibrosis

A recessive genetic disorder of the cell membranes. It results in the body producing a lot of thick sticky mucus in the air passages and in the pancreas.

There’s a 1 in 4 chance of a child having the disorder if both parents have or carry it

What is Polydactyl

A dominant genetic disorder where a person is born with extra fingers or toes. There’s a 50% chance if the baby’s parent has the disorder.

what is screening genetic disorders?

Looking at embryos in IVF to detect disorders or defects if it is the case so they can be terminated before being inserted into the womb

or

In natural pregnancy x rays which occur in the window for abortion if the parents choose to.

What is a phenotype

A physical characteristic.

Evolution

Charles Darwin’s discoveries

Evolution definition

Change of inherited characteristics of certain population over time via natural selection

Selective Breeding

* Animals that produces more meat
* Crops with disease resistance
* Dogs with a good, gentle temperament
* Decorative plants with big or unusual or unusual flowers

Genetic engineering

Modifying a genome and adding a gene responsible for a desirable characteristic

What is modified to make human insulin

bacteria

GM crops

\-Kills wild flowers and insects and educes farmland biodiversity

\-Some concerned of GMs effects on human consumption

\-A big concern is transplanted genes may get out into the natural environment e.g. causing super weeds resistant to herbicides being created

\-GM crops increase yield making more food

\-Golden rice is an example of a GM crop which helps prevent blindness (beta-carotene ) Helping devoloping countries with their lack in nutrients

Genetic engineering

A useful gene is isolated from one organism’s genome using enzymes and is inserted into a vector

the vector is usually a virus or a bacterial plasmid ( a fancy piece of circular DNA found in bacterial cells) depending on type of organism

when the vector is introduced to the target organism, the useful gene is inserted into its cells

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Uses for GE

Bacteria can be modified to produce human insulin

Genetically modified (GM) crops have had their genes modified, e.g. to improve size and quality of fruit, or make them resistant to disease, insects and herbicides

Sheep have been genetically engineered to produce substances like drugs, in their milk that can be used to treat human diseases

Research is happening for treatments to inherited disease caused by faulty genes by inserting working genes (Gene Therapy)

Antibiotic resistance

MRSA- super bug hard to get rid of and can be fatal

Fossils

Remains of organisms thousands of years ago

\-Gradual replacement of minerals- Teeth, bones and shells replaced by minerals to form a rock like substance. Surrounding sediment turns to rock but leaves the fossil distinct

\-From casts and impressions- organisms leaves an imprint in hardened clay. Animal burrow or plants roots or footprints

\-from preservation in places where no decay happens

Glaciers