Concept 1 + 2 - What is Life? + Molecules of Life

Question 1

How do we define life? 3 parts

Answer 1

What it consists of
1) Common set of elements (eg. proteins, carbos, fatty acids, nucleic acids)
2) Genetic information
3) Cells

What they do
1) Grow + change
2) Respond to the environment
//
3) Use molecules + make new molecules (eg.absorption)
4) Extract energy to use it (eg. photosynthesis - light energy -> chemical energy)

Overall
1) Evolve, exist in populations

Question 2

Metabolism

Answer 2

Extracting energy from the environment and converting it to useable forms by the organisms

eg. respiration, photosynthesis

Question 3

Why is information transmission, energy transfer, evolution basic to life?

Answer 3

1) Information transmission = organisms sending + receiving info:
- Within their own bodies
- With other organisms
- With the environment

2) Transfer energy = going from one form of energy to another
This is to do work → perform LIFE FUNCTION

3) Evolution = gradual change through natural selection
ANSWERING THE Q: ensures survival as the environment changes

Question 4

bacteria has 3000 genes, humans have 20,000 genes, why do we have the same 1,000 genes?

Answer 4

Concept = the GENES evolved here, not the organism

• Eukaryotic cells have a prokaryotic ancestor
• The 1000 genes ITSELF evolved
• BUT still were CONSERVED during evolution
• Conservation occurred likely as they are responsible for core functions in ALL CELLS
  Eg. transcription + translation

Question 5

Are viruses considered alive? YES

Answer 5

What it consists of
1) Contain nucleic acids

What they do
2) Can replicate

Overall
3) Evolve, adapt to the environment

Question 6

Are viruses considered alive? NO 3 parts

Answer 6

What it consists of
1) DO NOT have cells, no organelles

What they do
1) Can’t do INDEPENDENT replication (need a HOST CELL)
//
2) Cannot extract energy (eg. respire)

Question 7

Key features of cells 5 (3 parts)

Answer 7

Origin
1) All cells come from preexisting cells (eg. mutation)

Structure
2) Molecular + structural function of cells define their function
3) Cells are bounded by a membrane - compartmentalisation
4) Can form organised units with more complex function

Function
5) Communicate with other cells

Question 8

why are information transmission, energy transfer and evolution considered basic to life?

Answer 8

• Information transmission
  -> transmitting genetic information like DNA to offspring through REPRODUCTION
• Energy transfer
  -> converting external energy like sunlight into usable forms to do work -> sustains biological processes
• Evolution
  -> change in inherited characteristics of a population over time, driven by natural selection
• Natural selection
  -> process where individuals with advantageous traits survive and reproduce more successfully and pass this to their offspring, leading to a gradual increase in the frequency of these traits

Question 9

Cell Theory 3

Answer 9

Origin
1) All cells come from preexisting cells
(ie. mitosis)
2) Modern cells evolved from a common ancestor
3) All living organisms are made up of cells

Question 10

evidence that euk and prok share a common ancestor?

Answer 10

• Same genetic code (ie. DNA, RNA)

Question 11

How are living organisms similar?

Answer 11

• Same genetic code (ie. codons code for the same amino acids)
• Same chemical composition (ie. all proteins are made up of amino acids)
• Same cellular structure
  (SMALL TO BIG)

Question 12

What do similarities among living organisms indicate?

Answer 12

• All life on Earth has a COMMONA ANCESTOR (arnd 4 billion years ago)
• Became diverse through evolution + natural selection (change of genetic makeup)

Question 13

What created life on Earth - conditions? 2

Answer 13

1) Assumes early conditions on Earth = primordial soup AND reducing environment
- Soup = contains various chemicals needed for the building blocks of life
- Reducing environment = lack of o2 around, chemicals ready to share electrons
- -80 degrees celsius, 30 years

2) Extra-terrestrial origin
- Panspermia = theory that life originated elsewhere in the universe
- A comet was brought to earth by meteorites

Question 14

What created life on Earth - evidence? 2

Answer 14

1) Primordial soup + reducing environment
- MILLER-UREY experiment
- -80 degrees celsius over 30 years in TEST TUBE
- Found DNA + RNA, bases 20 amino acids, 3 and 6 carbon sugars
- fatty acids, NAD, Vitamin B6, Organic acids

2) Extra-terrestrial life
- Meteorite sample analsed
- Amino acids, DNA bases, sugars

Question 15

How did miller’s experiments support the idea that physical and chemical laws govern the processes of life at life’s origins? 5 MARKS

Answer 15

Q by chemical laws means that life started from basic molecules + evolved from there - THE BEGINNING OF LIFE!

EXPERIMENT + RESULTS
- Experiment produced molecules from each category (carbos, lipids, proteins, nucleic acids)
-
Proves that CHEMICAL EVOLUTION of biomolecules occurred

WHY IS SO SIGNIFICANT?
- Supports idea compared to if only 1 or 2 categories of molecules had been formed

LIMITATIONS
- Can’t be used to draw conclusions about what actually happened

Question 16

What created life on Earth - how does evidence point to life?

Answer 16

CHEMICAL EVOLUTION

• formation of simple molecules led to the formation of life forms!

Question 17

When did life arise on Earth? - ORDER OF EVENTS 9

Answer 17

1) Formation of Earth (too boiling hot)
2) First ocean - appearance of liquid water
3) Origin of life - life arose SOON after water!! (since h2o is so important!)

4) Photosynthesis
5) First colonial cyanobacteria
6) First eukaryotes

7) First photosynthetic eukaryotes (PLANT)
8) First multicellular eukaryotes (ANIMAL)
9) First fossils of multicelullar animals

Question 18

When did life begin? Evidence?

Answer 18

• Earth began 4.5 billion years ago
• But LIFE began around 3.5-3.7 billion years ago
  -> Stromatolites = cyanobacteria fossilisation
  -> Pillow basalt = trap liquid water

Question 19

Cambrian Explosion

Answer 19

• Most of the time period was cyanobacteria + single celled eukaryotes present
• THEN…rapid diversification of life 541 million years ago (lots of multicellular species)

Question 20

Why are there such large time gaps between bacteria, unicellular eukaryotes, terrestrial animals?

Answer 20

TIP
- Think how did a prokaryote become an eukaryote?

1) Mutation -> evolution
- mutations are fast
- but it takes a long time for them to SHOW and cause evolution

2) Long time for Invagination of membrane to form a nucleus

3) Long time for endosymbiosis

4) Ozone layer to protect from UV
- took a long time to form

Question 21

Stromatolites - what are they, conditions to grow

Answer 21

• Layers of limestone
• Grow in hypersaline (super salty) water

Question 22

Stromatolites - function?

Answer 22

• They can trap water -> therefore cyanobacteria inside their layers
• So allows for the fossilisation of bacteria! (ie. trace of dead organism)
• Assume cyanobacteria was there from when it was alive - around 3.7b years ago!

Question 23

NASA scientists are looking for stromatolite fossils on Mars. Explain why they are looking for stromatolites 2 marks

Answer 23

1) Stromatolites have trapped water containing cyanobacteria, dating back 3.5 billion years -> earliest
evidence of life on Earth.
2) Mars may have had water in its past, so stromatolites might hold trapped cyanobacteria/microbes that
are Martian.

Question 24

The scientist’s notes suggest this organism is an autotroph (diagram shows a cell w/ a mitochondria). Assuming that energy production is the same on
Mars, as it is on Earth, justify whether you agree with this statement 2 marks

Answer 24

1) Scientist’s statement not true because cell does not have a CHLOROPLAST or similar. (1 mark)
2) Cell would not be able to make its own glucose/ needs alternative source of energy

SO…2 KEY IDEAS TO MENTION
1) Chloroplast = autotroph
2) Source of energy = glucose

Question 25

Features of water + reason 5

Answer 25

1) High specific heat capacity 2) High melting + boiling point 3) High heat of vaporisation // 4) Cohesion 5) Adhesion // 6) Universal solvent --> all due to strong HYDROGEN BONDS between water MOLECULES that need to be DISRUPTED

Question 26

High specific heat capacity vs high boiling point vs high heat of vaporisation

Answer 26

- High specific heat capacity = amount of ENERGY to raise 1g of water by 1 degree (ONLY A SMALL AMOUNT, RAISING TEMP) - High heat of vaporisation = ENERGY (J) needed for liquid to turn into gas - High boiling point = TEMPERATURE at which liquid turns into gas (Boiling point is a RESULT of vaporisation)

Question 27

Cohesion vs Adhesion

Answer 27

ADHESION = THINK OF GLUE + PAPER Cohesion = hydrogen bonding between H2O molecules Adhesion = attraction of water to other molecules

Question 28

Boiling point + Melting point of water

Answer 28

- 0 degrees = melting point - 100 degrees = boiling point -> High compared to other similar covalent molecules -> Others like H2S are a gas at room temp, whereas H2O is mostly in liquid form on Earth

Question 29

Features of water - why is it a strong indicator of life? 5

Answer 29

1) High specific heat capacity = Lakes don't dry up and boil, survival of aquatic organisms (alongside vaporisation) 2) High melting + boiling point = Water is mostly in liquid form on Earth -> medium for bacterium to move through 3) High heat of vaporisation = Cooling for mammalian systems = Sweat ABSORBS larger amount of heat energy to EVAPORATE, causing cooling 4) Cohesion = Plants = water can flow from the roots to the leaves in a tree = Surface tension = creates a layer on water, spiders can walk on water 5) Adhesion = Plants = water transport, h2o molecules stick to xylem vessels in plants 6) Universal solvent = Salts and sugars = soluble -> transport in the blood = Lipids in membranes = insoluble

Question 30

Hydrogen bonding in water's 3 different states PIC

Answer 30

SOLID - Yes - Lattice, strong hydrogen bonds LIQUID - Yes - Hydrogen bonds constantly made +broken as h2o molecules move GAS - No - Can't form, water molecules are spread out, moving quickly

Question 31

Hydrogen bonding between water molecules - oxygen partial charge

Answer 31

In 1 water molecule, each oxygen atom will have TWO partial negative charges - this is from the 2 lone pairs BUT for dipole-dipole interactions with other molecules, we consider oxygen to only have ONE partial negative charge

Question 32

How does water molecules form hydrogen bonds?

Answer 32

- Oxygen is more electronegative than hydrogen - The oxygen atom in H2O pulls electrons towards itself, forming TWO partial negative charges on the oxygen atom ( for 2 lone pairs!!) - One partial positive charge on each hydrogen atom - ATOMS in neighbouring water molecules with opposite partial charges will be attracted to each other - Form a hydrogen bond

Question 33

What happens when salt is added to water?

Answer 33

BREAKS APART into its individual ions and DISSOLVES

Question 34

What happens when salt is added to water- WHY?

Answer 34

SALT = LATTICE OF IONS!!! - Water molecules cluster around the individual ions: - Negative/positive Ions + partial positive H/partial negative O form an interaction - ion-dipole interaction stronger than ionic bonds - Pull individual ions out of the lattice, move apart - Ionic bonds disrupted - Left with individual ions floating around

Question 35

What happens when a polar molecule eg. sucrose is added to water?

Answer 35

SUCROSE = Lattice of sucrose molecules - sucrose molecules held together by hydrogen bonds (have OH groups) - Water molecules form new hydrogen bonds with individual sucrose molecules (specifically the OH) - water-sucrose hydrogen bonds stronger than sucrose-sucrose hydrogen bond s - Pull them out of the lattice, disrupt their hydrogen bonds - BUT none of their atom-atom bonds (covalent) are broken or disrupted - Only hydrogen bonds are affected HENCE WILL NOT BREAK APART INTO SMALLER PIECES!! BUT WILL DISSOLVE

Question 36

Substances, when do they dissolve in water?

Answer 36

- solute-solvent forces stronger than solute-solute forces - allows solvent to pull apart the solute!

Question 37

Nonpolar substances in water

Answer 37

WON'T DISSOLVE - non-polar form strong dispersion forces due to long C chain - not as strong dispersion forces w/ water!

Question 38

Lipids + water (polar/non-polar) - why do they not mix?

Answer 38

- water forms strong hydrogen bonds - much stronge than lipid's dispersion forces - energetically unfavourable to break these strong forces, therefore don't mix, as hydrogen bonds form a network - DIFF TO DISSOLVING IS THAT HERE WE COMPARE STRENGTH OF INDIVIDUAL SOLVENT AND SOLUTE

Question 39

Polar molecules vs Nonpolar molecules vs Ionic substances in water PIC

Answer 39

POLAR MOLECULES - Attracted to each other - Will form dipole-dipole forces with each other - H is partial positive, O is partial negative (but has 2 lone pairs which can form 2 hydrogen bonds) NONPOLAR MOLECULES - Not attracted to each other - Nonpolar molecules will clump together, water molecules will be outside - Non polar molecules disrupt water's hydrogen bonding network, so they are pushed together AND - Non polar molecules eg. methane have a stronger attraction for each other than water (dispersion forces) IONIC SUBSTANCES - Most are soluble!! - Positive ion with partial positive negative etc. - Water will therefore tear off individual ions from the ionic lattice -> ion s will later disperse homogeneously through water

Question 40

Hydrophillic interaction vs Hydrophobic interaction

Answer 40

INTERACTION OF HYDROPHILLIC/HYDROPHOBIC MOLECULES W/ WATER Hydrophillic= - Ions + polar molecules = hydrophillic molecules - Attracted to water via dipole-dipole, hydrogen bonding or ion-dipole forces Hydrophobic= - Non polar molecules = hydrophobic - They stick together in water - do not associate

Question 41

pH of water?

Answer 41

- Neutral (pH7) at 25 degrees BUT also a.... - Weak acid (donate a H+) - Weak base (accept a H+)

Question 42

Why is pH important?

Answer 42

- impacts rates of biological reactions - changes 3D structure of biological molecules -> impacts function SO... - Compartmentalisation - eg. separate different parts of the body which work at diff optimum pH

Question 43

Major elements in life? 4

Answer 43

H,C,O,N - present as ions/ coordinating atoms in large organic complexes - present in biological molecules - carbon is the primary component!!

Question 44

Carbon - how many bonds

Answer 44

- 4 covalent bonds in total -> 4 single bonds -> 2 single, 1 double bonds -> 2 double bonds -> 1 single, 1 triple bond (carbon has 4 valence electrons, need 8 electrons in its outer shell)

Question 45

Carbohydrates function 3

Answer 45

MONOSACCHARIDE 1) Source of chemical energy = glucose for respiration POLYSACCHARIDE 2) Structural components = eg. cellulose in cell walls BASIC STRUCTURE 3) Carbon skeletons can be rearranged to form new molecules = ie. simple carbon structure can be used to make amino acids, nucleotides etc.

Question 46

What are carbohydrates general formula? Glucose?

Answer 46

(CH2O)n eg. glucose = c6h12o6

Question 47

Glycogen function? 2

Answer 47

STORE GLUCOSE AS GLYCOGEN - why? 1) Energy storage in animals, fungi, bacteria - chain of glucose so... - can be hydrolysed into glucose - release stored energy 2) Prevents cells from swelling - glycogen insoluble in water - PREVENT: lots of glucose in water = low WP in cells, so lots of energy wasted removing water from cells

Question 48

Cellulose function? 2

Answer 48

1) Easily degraded by chemicals - chains of glucose so... - easily broken down to release glucose for energy!! (ENERGY STORAGE) 2) Stable - BETA glycosidic bonds

Question 49

Why is branching present in polysaccharides?

Answer 49

Polysaccharides = amylopectin, glycogen - Branching allos rapid release of glucose

Question 50

Alpha + beta glucose - why ringed?

Answer 50

- Ring form is more stable in water

Question 51

Which polysaccharide is the most stable?

Answer 51

- Cellulose

Question 52

Types of RNA 3

Answer 52

1) mRNA - messenger ribonucleic acid 2) tRNA - transfer ribonucleic acid 3) rRNA - ribosomal ribonucleic acid

Question 53

2 types of genes in DNA

Answer 53

- Non-coding genes in DNA = template (3' end to 5' end) - Coding genes in DNA (5' end to 3' end) --> transcription, mRNA is made using coding strand 5' to 3' (copied pasted, except all T's changed to U's)

Question 54

Functions of a protein 5

Answer 54

1) Structural (keratin in hair) 2) Hormones 3) Contractile (help muscles contract) 4) Enzymes 5) Transport (eg. membrane) **CYTOSKELETON - made up of proteins like actin, tubulin, fibrous proteins 5) Defence (antibodies)

Question 55

primary, secondary, tertiary structure of protein - what affects what?

Answer 55

- Tertiary structure is affected by primary, secondary - BUT primary/secondary will not be affected by tertiary (HIGHER AFFECTED BY LOWER, LOWER NOT AFFECTED BY HIGHER)

Question 56

HOW IS PROTEIN STRUCTURE RELATED TO ITS FUNCTION?

Answer 56

- Proteins have a HIGHLY SPECIFIC function - Function is dependent on its SHAPE + FOLDING - A protein’s 3D shape is dependent ONLY on its TERTIARY STRUCTURE -> Example = an enzyme’s active site is a tertiary structure. This active site is specific to a substrate

Question 57

PRIMARY → SECONDARY → TERTIARY RELATIONSHIP

Answer 57

PRIMARY = sequence of amino acids in a polypeptide chain SECONDARY = ON THE SAME CHAIN, - hydrogen bonds between carboxyl + amine groups → alpha helix + beta sheets formed TERTIARY = SECONDARY STRUCTURES folded into tertiary structure (still within ONE CHAIN) = complex 3D shape - forces between R groups - ONLY tertiary structure will affect 3D protein shape - Protein SHAPE impacts protein FUNCTION (eg. enzyme active site, tertiary structure)

Question 58

Tertiary structure - what types of forces between R groups?

Answer 58

- Hydrogen bonding - Dipole-dipole - Ion-dipole - Ionic - Disulfide bridges (covalent bonds) S-S - Dispersion forces

Question 59

where is protein, nucleic acid, carbohydrates, lipids found in a cell?

Answer 59

Proteins - cytoskeleton - enzymes Nucleic acids - chromosomes, nucleus - mitochondria, chloroplasts Lipids - cell membrane (phospholipids) - storage vacuoles Carbos - cell walls (cellulose) - storage vacuoles

Question 60

what is nucleic acid, carbohydrates, lipids function?

Answer 60

Nucleic Acids - DNA: Stores genetic information - RNA: Helps make proteins Carbohydrates (think glucose) - Provide energy for the body - Store energy for later use Lipids - Store energy for long-term use - Make up cell membranes - Insulate and protect organs

Question 61

How does amino acid structure allow for protein to perform so many functions?

Answer 61

- diff (R groups) - These side chains can be nonpolar, positively or negatively charged, or polar but uncharged - form diff interactions - Primary structure flexibility: diff sequence of amino acids - diff interactions = diff tertiary structure = diff FOLDING + 3D SHAPE = diff function

Question 62

How is proteins (eg. enzymes) specific to other molecules 2

Answer 62

1) Shape - must have a general 'fit' into each other 2) Chemistry - surface R groups on molecule + enzyme interact w/ each other

Question 63

What is protein denaturation

Answer 63

What is it? - when the secondary + tertiary STRUCTURE of a protein is changed - due to disrupted side chains, unfolding of protein, breaking h2 bonds of the structure etc.

Question 64

How would pH, temp, addition of polar/nonpolar molecule cause denaturation of a protein - general

Answer 64

DENATURATION - Change in 3d shape - change in tertiary structure - Looking at changes in R GROUPS - NOT carboxyl or amine - although polar, all are involved in peptide bond except the ends

Question 65

How would pH, temp, addition of polar/nonpolar molecule cause denaturation of a protein - temp

Answer 65

- increase kinetic energy - R groups move randomly - IMF disrupted - change in folding

Question 66

How would pH, temp, addition of polar/nonpolar molecule cause denaturation of a protein - pH

Answer 66

- change in H+ conc - IONIC R groups will be affected - will form ionic bonds with H+, breaking R group interactions AND - R groups like carboxyl will become COOH will become COO- due to Le chateleir??

Question 67

How would pH, temp, addition of polar/nonpolar molecule cause denaturation of a protein - polar/nonpolar

Answer 67

POLAR - dipole-dipole +hydrogen bonds between R GROUPS disrupted - R groups will form attractions with polar molecules instead NONPOLAR - same, dispersion forces between R GROUPS

Question 68

Protein denaturation - conditions, explanation

Answer 68

1) High temp - disrupt hydrogen bonding etc. , excited and move apart 2) pH changes - alter charges on the r groups of acidic and basic amino acids 3) high concentration of polar molecules - protein is meant to have interactions with its substrate - but now making dipole dipole and hydrogen bonds with other molecules 4) high concentration of non-polar molecules - hydrophobic molecules interact with other nonpolar substances, causing protein to change shape

Question 69

explain why the structure of a protein and its function are intimiately interconnected. drescribe the forces that hold proteins in their functional conformation

Answer 69

- hydrogen bonds, dispersion forces, dipole-dipole, ionic 1) R group interactions impact folding, therefore 3D shape of protein -> shape impacts function - general fit w/ substrate 2) Specific R group positioning on surface of protein enzyme will INTERACT w/ substrate 3)

Question 70

Properties of a lipid - solubility

Answer 70

1) Insoluble in water - lipids (so large) form strong dispersion forces with each other - form stronger interaction btwn lipids vs lipids + water, so clump together 2) Soluble in organic solvents

Question 71

Other properties of lipids

Answer 71

1) Composed mainly of C,H, and O 2) Different from carbos due to smaller proportion of oxygen 3) May contain other elements (eg. phosphorus, nitrogen)

Question 72

Saturated vs unsaturated fatty acids

Answer 72

SATURATED = lots of hydrogens So...all carbons on main chain has a SINGLE BOND UNSATURATED = not many hydrogens So...carbons on main chain has a DOUBLE BOND

Question 73

Saturated vs unsaturated fatty acids - difference in properties - solid or liquid at room temp? PIC

Answer 73

UNSATURATED = double bonds are inflexible, causes the structure to BEND SO...tends to be oil at room temp - unable to pack closely and enter the solid phase SATURATED = single bonds can rotate easily SO...typically fats and solids

Question 74

Uses of lipids/fats

Answer 74

1) Energy storage - contains lots of energy which can be broken down later for work - stores much more than glucose - long carbon chain! This can be RELEASED slowly for growth 2) Insulate heat + increase buoyancy - eg. blubber in whales

Question 75

Uses of proteins

Answer 75

- Building cells, differentiation and growth -> Source of amino acids to make ITS OWN cellular proteins

Question 76

Cholesterol uses 2

Answer 76

1) Important part of the cell membrane 2) Precursor for chemical messengers + vitamins

Question 77

2 structures phospholipids form

Answer 77

IF AIR + WATER - membrane SURROUNDED BY WATER - micelle (ball)

Question 78

Why are functional groups important?

Answer 78

- impacts polarity of the molecule - therefore impacts how the molecule interacts w/ other molecules!!

Question 79

Biological polymers definition

Answer 79

- long chains of repeating subunits (monomers)

Question 80

glycosidic bond same as?

Answer 80

Ester bond

Question 81

Polynucleotide strands

Answer 81

- nucleic acid = polymer, like DNA - monomer = nucleotide - monomers in one strand = polynucleotide strand STRANDS DO NOT BRANCH

Question 82

Zwitter ion

Answer 82

- amino acid that is neutral (contain equal no. of positive and negative charge) - from carboxyl and nh2 amine group

Question 83

Peptide bond - other name

Answer 83

- amide bond

Question 84

Bonds in a tertiary structure 3

Answer 84

- BONDING BETWEEN THE R GROUPS 1) Hydrogen bonds 2) Ionic bonds - between r groups with positive and negative charges 3) Disulphide bridges (covalent bond) - between 2 cystine amino acids (these contain sulphur) - 2 sulphurs come together to form a covalent bond

Question 85

Phospholipid - what type of compound is it?

Answer 85

Amphipatic compound

Question 86

electronegativity definition

Answer 86

ability of an atom to attract a bonded pair of electrons towards itself in a covalent bond

Question 87

What is the role that hydrogen bonding plays in stabilising glycogen + cellulose? 2 marks

Answer 87

1) WHERE DOES HYDROGEN BONDING OCCUR? - Hydrogen bonding occurs between hydroxyl groups of alpha and beta glucose monomers (any carbon with OH group) 2) DIFF STRUCTURES FORMED - In Glycogen, hydrogen bonding give it its structure (helical in this case). - Whereas hydrogen bonding between adjacent molecules in cellulose result in bundles or fibers.

Question 88

role cyanobacteria played in creating conditions that allowed for the evolution of terrestrial life.

Answer 88

1) cyanobacteria are photosynthetic and this increased oxygen levels in the atmosphere. 2) increased oxygen in the atmosphere led to the production of ozone. Ozone blocks UV radiation from the sun, thus shielding the land. This allowed life to colonise land without being irradiated by intense UV.

Question 89

three pieces of evidence that supported the statement that mitochondria became part of the eukaryotic cell through primary endosymbiosis.

Answer 89

(1) like most prokaryotes, mitochondria has circular genomes; (2) mitochondria have their own ribosomes that are more bacterial-like than those in the cytosol (3) mitochondrial genomes show common ancestry with purple bacteria; (4) mitochondria use FtsZ-based contractile rings for division like prokaryotes; and others.

Question 90

You were told the stain colours negatively charged molecules blue/purple - WHAT DOES THIS REPRESENT?

Answer 90

The simplest explanation is that the purple stained organelles are nuclei because DNA is negatively charged due to its phosphate backbone and the light purple cytoplasmic staining is RNA and DNA in mitochondria. Red blood cells don’t have nuclei so are not stained purple.