Origin of cells

what were conditions like at the start of the world (pre-biotic)?

very little oxygen → no ozone layer → high uv
ammonia, methane and carbon dioxide

what started to form at the start of the earth

carbon compounds → amino acids → proteins

why was the temperature so high at the start?

high levels of CO₂ and methane

why was there more solar energy at the start? what did this lead to?

less magnetic field → lead to comet and asteroid impacts

organic

contains carbon and hydrogen

inorganic

does not contain carbon and hydrogen

what started to rise in levels in the early atmosphere?

oxygen

what did increasing levels of oxygen lead to?

ozone layer formed → less UV

what reduced in levels as oxygen increased?

CO₂

what did decreasing levels of CO₂ lead to?

reduced greenhouse effect →earth cooled and became less acidic

what are the 8 life processes?

Movement
Response

Homeostasis
Metabolism

Growth
Reproduction
Excretion
Nutrition

“Mr H.M Gren”

what is cell theory?

1. cells are the smallest unit of life

2. every living thing is composed of cells

3. cells come from other pre-existing cells

who disproved spontaneous generation?

Louis Pasteur

How did Louis Pasteur disprove the well known theory?

he heated broth in a swan neck flask to kill off any bacteria. the flasks allow airflow but stop microbes from entering. no microbial growth occurred on the broth. however, when he didn’t heat the broth or cut off the swan neck, growth did occur.

what is a cell? ( 4 conditions)

1. must be surrounded by a membrane

2. must contain genetic material

3. will contain enzymes

4. has its own energy release system

how was the first cell made?

1. formation of simple organic matter

2. catalysts

3. self - assembly of carbon compounds into polymers

4. compartmentalisation - membrane develops

5. self - replication of molecules

how was the first pre-biotic ocean described?

hot soup

what experiment did MIller and Urey do?

mixed ammonia, hydrogen and methane in a container. they boiled and condensed it continuously using electrodes to stimulate lightning_.

what was the outcome of Miller and Urey’s experiment?

the mixture produced multiple carbon compounds including over 20 amino acids, showing that they could’ve formed spontaneously of earth before life evolved.

vesicles

small droplets of fluid enclosed in a membrane.

what is membrane composed of?

phospholipids

amphipathic

having both hydrophilic and hydrophobic parts.

what did phospholipids in early oceans form into?

spheres or bilayers

what was presumed to have come before DNA?

RNA

LUCA

Last universal common ancestor

what was LUCA?

simple single celled autotrophic ( able to photosynthesise) microbe with RNA that formed 2.5 - 3.5 billion years ago.

what are the three theorised branches of LUCA

bacteria, eukarya and archaea

what is the 64-word code?

the genetic code, which uses codons to specify 20 essential amino acids with a total of 64 possible codon combinations

what does paleontology provide?

evidence on evolutionary pathways which helps to date cells

stromatolite

formed when mats of cyanobacteria in shallow sea water trap sediment and secrete calcium carbonate slowly building rocky mounds over thousands of years.

what temps do hydrothermal fluids emerge to?

up to 400 C

what does hydrothermal fluid mix with and what temp does it become?

water - around 60 C

what does hydrothermal fluid contain high levels of?

hydrogen, methane, ammonia and sulphides

what are hydrothermal vents theorised to have been the site of?

the first cells evolving from non-living matter