A2.1 - A2.2 Biology

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HL IB Biology section A2.1 and A2.2

53 Terms

1

Eukaryotes

  • Belonging to multicellular organisms

  • Protista, Fungi, Plants, Animals

  • Believed to have evolved from prokaryotic cells

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2

Golgi body

Stores, modifies and packages proteins

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3

Free Ribosomes (E)

Synthesis of proteins for use IN the cell

80S

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4

rER (rough Endoplasmic Reticulum)

Synthesis of proteins for use OUTSIDE of the cell

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5

Lysosomes

Contain digestive enzymes, and can fuse with vesicles containing damaged organelles

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6

Nucleus

Surrounded by a double membrane with pores, contains the cell’s DNA

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7

Mitochondria

The site of Aerobic respiration- the production of ATP energy

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8

Plasma membrane (E)

  • Controls the movement of materials into and out of the cell

  • Allows cell to maintain concentrations of substances that are very different from those in the surrounding environment

  • Semi-permeability replies on the lipid bilayer

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9

Cytoplasm (E)

  • Fluid within the plasma membrane where organelles occur

  • Mainly composed of water with many substances dissolved or suspended in it

  • Enzymes catalyze different chem reactions

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10

Prokaryotes

Belong to single celled organisms

Ex. Bacteria

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11

Cell Wall (peptidoglycan)

A rigid non-cellulose structure that surrounds cells of bacteria or plant cells

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12

Plasma membrane (P)

A phospholipid bilayer that surrounds the cell

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13

Cytoplasm (P)

The gel-like fluid inside the cell membrane where the reactions of metabolism occur

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14

Pili

Hair-like protein structure that allows bacteria to attach to things

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15

Flagella

Long, thin, whip-like structures, made from the protein ‘flagellin’ that enables movement

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16

Ribosomes (P)

Organelles made of protein and RNA that direct protein synthesis

70S

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17

Nucleoid

A dense region of DNA in a prokaryotic cell

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18

Conditions of early earth

  • Pre-biotic period (no life)

  • Lack of O2 = lack of ozone

    (due to O reacting with other elements)

  • Higher concentration of methane

    (Due to intense volcanic activity & meteorite strikes)

  • Higher concentration of CO2

    (Probably due to emission from volcanoes)

  • Higher temps

  • High levels of ultraviolet light penetration

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19

The pre-biotic formation of Carbon Compounds

Formed spontaneously by chemical processes that do not occur today

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20

Why conditions on Earth today make spontaneous formation of organic carbon compounds less likely than they were

  • higher O2 levels (0% to 20%) causing the ozone layer to form

  • Drop in CO2

  • Reduction in greenhouse effect

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21

Evidence that cells are living

  • Cells use ATP energy to maintain highly ordered state

  • Cells can divide or reproduce on their own to make new cells

  • Cells can evolve

  • Cells are separate from their environment but can still communicate with other cells

  • Cells can receive and respond to stimuli

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22

Why are viruses are considered non-living

  • Non-cellular and lack organelles to carry out metabolism and protein synthesis independently

  • Can only replicate in living cells using their components

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23

3 common features of cells

  1. A stable, semi-permeable membrane

  2. Genetic material able to be passed on

  3. Metabolic processes that allow ATP energy generation (enables growth, reproduction and self-maintenance)

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24

Origin of carbon compounds

Molecules were mainly made up of C H O, some N P S

Living things make these by action of enzymes in their cells

Synthesis of simple organic molecules needed to occur for non-living materials to = life

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25

Miller-Urey Experiment

Passed steam through a mixture of H2 and CH4 and NH3

Used electrical discharge to simulate lightning

Amino acids, fatty acids and sugars were produced

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26

Spontaneous formation of vesicles

By coalescence (merging) of fatty acids into spherical bilayers

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27

Importance of phospholipids in the formation of cells & their components

If phospholipids were part of the carbon compounds on pre-biotic earth, they would have self-assembled into bilayers and vesicles would likely have formed

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28

Why was RNA was presumed as the first genetic material in living organisms and not DNA

  • Can form as an enzyme

  • Can act as a catalyst

  • Can replicate

  • Earliest life forms may have used it to store genetic material (RNA world hypothesis)

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29

LUCA

  • All life forms share a common ancestor

  • Likely that other forms of life evolved at the same time, but became extinct

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30

What is evidence for LUCA

Characteristics:

  • Anaerobic (survived without oxygen)

  • Carbon fixing (convertesd CO2 into glucose)

  • Hydrogen dependent

  • Nitrogen fixing (converted N2 into NH3)

  • Thermophilic (survived high temps)

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31

Outline the cell theory

  • Cells are the smallest unit of life

  • All organisms are made of cells

  • All cells come pre-existing cells

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32

Outline cells as the base of all living things

The cell is the basic structural, functional, and biological unit of all living organisms

Can be multicellular or unicellular

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33

Calculating the magnification, size or actual size of an image

Magnification = size of image / actual size of specimen

1mm = 1000um

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34

Light microscopes

Simple (1 lens), compound (2 lenses: ocular lens and objective lenses)

Can magnify up to ~1500x

4× 10× 40x

Max resolution: 0.2um (200nm)

Reveals only the structure of the cell

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35

Electron microscopes

Scanning, transmission

Can magnify up to ~1,000,000x (1mill)

Uses beams of electrons to cause shorter wavelengths (more energy = more resolution)

Resolution: 0.001um (1nm)

Reveals the ultra structure of cells

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36

Developments in microscopy

  • 17th century, lenses were used

  • 1665, the cell was named

  • 1670: first living cell was seen

  • 1931: Germans invented light microscopes

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37

3 structures common to cells in all living organisms

  • Cell membrane

  • Cytoplasm

  • DNA

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38

Atypical Cell

Organisms that do not follow the typical structure and patterns in a eukaryotic cell

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39

Describe the origin of eukaryotic cells by endosymbiosis

Began as prokaryotic cells, but were swallowed up by other prokaryotes until they became eukaryotes (gained mitochondria and or chloroplasts)

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40

3 features that distinguish Eukaryotic cells from Prokaryotic cells

  1. Nucleus

  2. Ribosomes (different sizes)

  3. Mitochondria

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41

Advantages to Multicellularity

Multicellular organisms:

  • Tend to have a longer lifespan

  • Are generally larger than unicellular

  • Are more complex

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42

Processes required for the survival of organisms

  • Homeostasis (constant internal environment)

  • Metabolism (sun of biochem rxns)

  • Nutrition

  • Excretion

  • Growth

  • Response to stimuli

  • Reproduction

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43

What kind of environment did LUCA live in?

  • High concentration of H2 CO2 and Fe

  • Conditions found in and around hydrothermal vents

  • Most suited to life were the alkaline hydrothermal vents (white smokers)

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44

Slime Capsule (Glycocalyx)

Thick polysaccharide layer used for protection against desiccation (drying out) and phagocytosis

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45

Phagocytosis

When a cell eats / consumes another cell

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46

Naked DNA (P)

Usually only 1 DNA strand that is circular or forms a loop

Not associated with histone proteins

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47

Plasmid (P)

Independent circular DNA molecule that may be transferred between bacteria (horizontal gene transfer)

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48

DORA

  • DNA:

    • P- DNA is naked, it is circular, usually has no introns

    • E- DNA is bound to protein, linear, usually has introns

  • Organelles:

    • Not membrane bound vs membrane bound, 70S vs 80S, no nucleus vs nucleus

  • Reproduction:

    • P- Binary fission, single chromosome

    • E- Mitosis and meiosis, chromosomes paired

  • Average Size:

    • P- (~1-5um) E- (~10-100um)

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49

4 types of Atypical cells

  • Red blood cells

    • Do not have a nucleus

  • Phloem Sieve Tube Elements

    • No nucleus and lack many other organelles

    • Have sieve tubes, each of which is connected to a companion cell which helps the element survive

  • Skeletal Muscle

    • Cells fuse together to make a multinucleated cell

  • Aseptate Fungal Hyphae

    • Fungi have thread-like structures called hyphae that are separated into cells by septa

    • These have NO septa = multinucleated

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50

Endosymbiotic Theory

Mitochondria and Chloroplasts were once prokaryotic but were engulfed by larger prokaryotes via phagocytosis

Animal Cells = Mitochondria

Plant Cells = Mitochondria and Chloroplasts

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51

Cell Differentiation

  • Stem cells can become anything (turn into specialized cells)

  • Only express genes that code for the required proteins

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52

Housekeeper Genes

  • genes that are always needed in a cell

  • Regulate processes required (ex. metabolism, growth, DNA replication, transcription)

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53

Protocell

It is a compartment enclosed in a phospholipid membrane.

It is likely that self-replicating molecules were encapsulated by this membrane

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