HL Biology Unit 3: Origins of Cells

cell

structural and functional unit of all living organisms

building blocks of life

TRILLIONS

cell makeup

2/3% water

mixture of molecules- lipids, proteins, carbs

metabolic reactions

functions within cells that support our body’s needs

cellular respiration

breaks down and turns sugar into energy

atoms

molecules

organelles

cell

tissue

organs

systems

organisms

levels of organisms

organelles

parts of a cell with individual functions

tissue

cells combine to do something

organs

tissues combine to work together

cell processes

metabolism, reproduction, sensitivity, homeostasis, excretion, growth

cell theory

the cell is the smallest unit of life, all living things are composed of cells, cells can only arise from preexisting cells

carbohydrates, lipids, proteins, nucleic acids

four classes of carbon compounds

hydrogen, oxygen, nitrogen, carbon

four main elements to build a living organism

HONC to build a living organism

saying for how to build a living organism

1. carbon is very abundant on Earth

2. Carbon can form up to four covalent bonds with other atoms

why is carbon the basis for all compounds of life?

self-sustaining

carry out functions autonomously

characteristics of living organisms

need a host to live

cannot carry out life functions autonomously

characteristics of non-living organisms

no, they must rely on host cells and cannot self-replicate

are viruses living?

metabolism, reproduction, sensitivity, homeostasis, excretion, nutrition, growth

7 functional features of life

MR SHENG

Mnemonic device for 7 function features of life

metabolism

undertakes essential chemical reactions

reproduction

produce offspring, either sexually or asexually

sensitivity

responsive to internal and external stimuli

homeostasis

maintains a stable internal environment

excretion

able to remove toxic waste products

nutrition

exchanges material with environment

growth

changes shape, size, or position

container

something to house the molecules and structures that make all features possible

Spontaneous Theory

living organisms can be produced by non-living things

Aristotle

claimed life came from non-living things if the material contained pneuma

debunked

pneuma

vital heat

Abiogenesis Theory

the first cells must have come from non-living matter through natural processes

The Soup Theory

chemical evolution preceded life formation

life evolved in warm oceans where no O₂ was in the air

high temperatures, high UV, reducing atmosphere, high CO₂ and a water source

Some ways the atmosphere was different back then

Miller-Urey Experiment

demonstrated the synthesis of organic compounds from non-living material

“primitive” atmosphere was similar to the conditions

water boiled to vapor, vapor mixed with gases, mixture exposed to lightning, mixture cooled and became liquid

Science is the study of….

observable facts

protocell formation

formation of membranes

in water, fatty acids form micells

bilayers

when mixed with H₂O, phospholipids form these

synthesized DNA

proteins need…

self-replicated proteins

DNA needs…

RNA

what is presumed to have been the first genetic material?

• can self-replicate

• has catalytic activity

what can RNA do in the same way as DNA?

Water

what is the common molecule between all theories of cell formation?

role of water

formation of cells NEED water

water’s polarity causes non-polar lipids to form bilayers

LUCA

all Earth organisms share common characteristics

genetic code is universal

1. universality of genetic code

2. conserved gene sequence

What are the two pieces of evidence for LUCA?

obligate anaerobe, chemoautotroph, thermophilic

Characteristics of LUCA

molecular clock

estimates the time since divergence based on the number of mutations

1. act as a catalytic agent

2. act as a self-replicating genetic material

what must a cell do to be self-sustaining?

• ribosomes

• cytosol

• cell membrane

• genetic material

what 4 basic structures do all cells have?

prokaryotes

cells with only these four structures

archaea and bacteria

what are two examples of prokaryotes?

protists, fungi, plant, and animal cells

what are examples of eukaryotes?

eukaryote

more complex cells

endosymbiosis

the process by which eukaryotes evolved from prokaryotes

1. ancestral prokaryote

2. nucleus formation

3. endosymbiosis

4. eukaryotic cell

what are the four steps that turn a prokaryote into a eukaryote?

radiometric dating, analyzing fossilized biomarkers

microscopy

what are three methods to dating things?

membranes, antibiotics, DNA, division, ribosomes

what is the evidence of endosymbiosis?

• allows organisms to exceed Surface Area: Volume ratio

• allows longer lifespans

• complexity through different types of cells

what are the advantages of multicellularity?

• when cell growth is irregular, cancer can occur

what are the challenges of multicellularity?

differentiation

• specialized tissues due to different cells

• when genes are “switched on and off”

• may be a result of environmental changes

1. inorganic molecules

2. organic monomers

3. self-replicating Carbon polymers

4. protocell formation

5. LUCA

6. prokaryotes

7. endosymbiosis

8. eukaryotes

9. multicellularity

the process of the origin of cells

binary fission

how do prokaryotic cells divide?

fission, mitosis, meiosis

how do eukaryotic cells divide?