Genes Flashcards
who proposed the theory of evolution ?
Charles Darwin
what island did he travel to , to collect evidence about his theory
the Galápagos
what was the peppered moth theory
Tutt suggested that the peppered moths were an example of natural selection. He recognized that the camouflage of the light moth no longer worked in the dark forest. Dark moths live longer in a dark forest, so they had more time to breed. All living things respond to natural selection.
which moth was more common 100 years ago
the dark moth was more common due to industrial revolution
which moth would be more common nowadays ?
clean moth would be more common as we don’t burn coal anymore making the tree’s cleaner.
how many species are there on earth
8.7 million different species, they appeared by evolution
what is variation
difference/change in same species
what is natural selection
process where species change over time in response to changes in environment , or competition between organisms , in order for species to survive.
what year did Charles go to the Galapagos islands
1831
how did Charles develop the theory of evolution
he saw that on the galapagos islands the birds all had different beaks to help them eat
Name 2facts about the dodo
- Dodos live in islands of Mauritus,
- soldiers found dodos and used them for fresh meat
why did the dodo become extinct
over harvesting of the birds , combined with habitat loss and a losing competition and newly introduced animals was too much for dodos to survive
why did hawaiian snails get extinct
they usually ate leaves from trees , but due to deforestation these snails lost their food. when eating they reduced fungi on trees , but as snails extinct , fungi grew
how did passenger pigeons get extinct
last pigeon died in 1914. they were hunted and weren’t able to breed. this made the population fragile. By shooting them, they completely extinct
what is captive breeding ?
captive breeding is when animals are kept in zoo’s to help them breed and keep them healthy to later allow them to go back to freedom.
what is a gene bank
a gene bank is when they collect genes to replant them or use them to help return animals
what are chromosomes
chromosomes are packages of DNA ( Deoxyribonucleic acid ) The chromosomes are found in the nucleus of each cell. Human body cells each contain 23 pairs of chromosomes, half of which are from each parent. So, human gametes (eggs and sperm) each contain 23 chromosomes. When an egg is fertilised by a sperm, it becomes a cell with 23 pairs of chromosomes.
what does DNA do ?
DNA decides everything about us, from the colour of our to how we digest food and how tall we grow, so it is very important to protect it from damage. Each section of a chromosomes that controls one of our features is called a gene
what can mutations cause?
- mutations to our DNA can cause cancer
- mutations that we pass onto our children can cause inherited diseases such as cystic fibrosis or sickle cell anaemia
who discovered the structure of the DNA
Rosalind Franklin , Maurice Wilkins ,James Watson and Francis crick discovered the double-helix structure of DNA, which formed the basis for modern biotechnology
what does mutation mean
A mutation is a change in the structure of a gene, the unit of heredity. Genes are made of deoxyribonucleic acid (DNA)
what is an allele
different versions of a gene
what is a dominant allele
an allele that will always how through in our feature
what is a recessive allele
an allele that will only show through if we inherit it from both parents.
name some advantages of genetic modification
- quicker than selective breeding e.g genes from jellyfish have been used to produce crops that glow in the dark when lacking water
- allows scientist to learn about diseases e.g. mice have been modified to model human diseases including Alzheimer’s, cancer and diabetes.
- improved resistance to insect attack e.g. a taste gene in tomatoes has been charged so that ants wouldn’t eat them.
name some disadvantages of genetic modification
- insects may become pesticide - resistant if constantly eat pesticide forming plants
- may be bad for human health
- people may use it to ‘design’ children with particular characteristics such as high intelligence or good looks
what is genetic modification
a technique in which scientists insert foreign genes into organisms to change their characteristics.
what does extinct mean
when no more individuals of a species remain anywhere in the world
what is mutation
change to DNA that can cause disease
what is a gene
section of DNA that contains the information for a characteristic
what is natural selection
process by which the organisms with the characteristics that are most suited to environment survive and reproduce passing on their genes
what is DNA
chemical that contains all the information needed to make an organism
