DNA
deoxyribonucleic acid
chemical that all genetic material in a cell is made up from
chromosome
long, thread like stucture located inside nucleus of cell
how is dna found?
as a polymer - made up of 2 strands coiled together in shape of a double helix
gene
small section of dna found on a chromosome
what does a gene code for?
particular sequence of amino acids which are put together to make a specific protein
genome
entire set of genetic material
why is it important that scientists are aware of the human genome
- identify genes linked to diseases -> help develop effective treatments
- migration of populations
- ancestry
meiosis process (5)
- cell duplicates genetic info
- chromosomes arrange into pairs
- pairs line up in centre in first division
- pairs are pulled apart so each new cell has 1 copy of each
- chromosomes line up again and arms of them are pulled apart
male and female chromosome labels
male : XY
female : XX
what are fossils
remains of plants an animals from thousands of years previous
how do fossils form?
- gradual replacement by minerals
- casts and impressions
- preservation in places where no decay happens
fossils gradual replacement
teeth, shells, bones can last long time when buried
eventually replaced by minerals as they decay forming rock-like substances shaped like original part
fossils casts and impressions
fossils can be formed when an organism is buried in soft material eg clay
clay later hardens around it and organism decays, leaving cast of itself
eg. footprints, burrows, roots
fossils preservation
in amber and tar pits theres no oxygen or moisture so decay microbes cant survive
what do fossils show?
how much or how little organisms have evolved over time
why are many remains undiscovered?
many early life forms were soft bodied - soft tissue can decay completely
some fossils could have been destroyed by geological activity
Linnaean System order (7)
- kingdom
- phylum
- class
- order
- family
- genus
- species
what does the linnaean system do?
groups living things according to their characteristics and structures that make them up
three domain system
- archaea
- bacteria
- eukaryota
archaea domain
organisms are primitive bacteria
often found in extreme places eg. hot springs, salt lakes
bacteria domain
organisms are true bacteria eg. E. coli
often look similar to archaea but lots of biochemical differences between them
eukaryota domain
broad range of organisms
eg. fungi, plants, animals and protists
binomal system names
first part of name is the genus that an organism belongs to -> ancestry
second part refers to species
eg. humans called Homo sapiens
‘homo’ - genus
‘sapiens’ - species
mutation
permanent random change in an organisms dna sequence
due to replication, errors of environmental factors eg. UV light
