Molecules And Cells Flashcards Preview

Botany PSC103 > Molecules And Cells > Flashcards

Flashcards in Molecules And Cells Deck (30):
1

What main chemical bonds are formed?

Covalent - Electrons shared as in molecular oxygen and carbon compounds.
Hydrogen - weak forces in water - surface tension and in DNA
Ionic - One partner steals an electron from the other e.g.. salt NaCl
Peptide - covalent bonds in protein
Sulphur - these covalent bonds help proteins fold (S-S)

2

What are the 6 most common elements in plants?

Calcium,magnesium and potassium make up 99.95% of dry matter in plants.

3

What are Macronutrients composed of?

Nitrogen - Proteins,nucleic acids and alkaloids
Carbon C - Organic molecules
Hydrogen H2 - Organic molecules
Oxygen O2 - Organic molecules
Phosphorous P - Proteins,Nucleic acids
Sulphur S - proteins
Calcium Ca - Cell wall cytoplasm
Magnesium Mg - Chlorophyll
Potassium K - Vacuoles, Cytoplasm

4

What is energy and what happens to energy?

Energy is the ability to do work and it can not be created or destroyed only changed(stored)

5

What work do plants do?

Make bonds -
Form molecules (carbohydrates,proteins,nucleic acids,lipids) which result in growth and development.

6

What do chemical bonds do?

Hold molecules together
Take energy to form
Require energy to break
Are a way of storing energy

7

What role does water have in plants ?

Makes up solutions in which reactions occur (polar solvent)
Creates pressure within cells to make plant organs rigid(Turgor pressure)
Used in chemical reactions
Used to transport materials around the plant

8

What are the consequences of polarity of water molecules and hydrogen molecules bonding in water?

Highly effective solvent and can easily dissolve salts,many gases and polar organic compounds.
Cohesion – water molecules can be drawn from soil up through the roots and tree trunks to leaves to a height of 110 metres.
High specific heat – cools leaves by evaporation; buffer temperature changes in and near large bodies of water. Highest density at 4oC; water ice floats; liquid water remains under ice on lakes in winter.

9

What are plant synthesised molecules?

Carbohydrates,Proteins,Nucleic acid
Lipids.

10

What are carbohydrates?

Compounds containing Carbon, Hydrogen and Oxygen.

11

What is the function if carbohydrates in plants?

Energy storage such as sugars and starch. Structural building materials - cellulose in plants.
Product of photosynthesis - Carbon from CO2 - hydrogen from water, oxygen from water.

12

What does Monosaccharide mean?

Mono = one Saccharide = sugar

13

What does Disaccharide mean?

Di = Two Sugars (Two monosaccharides bonded together)

14

What is an example of a disaccharide?

Sucrose C6H12O6 + C6H12O6 = C12H22O11+H2O

15

What are micronutrients?

They are in tiny amounts and they function as co-factors. They help the biological protein catalysts - enzymes perform their functions.

16

What does starch do in plants?

Store carbohydrate energy, they are long and slightly branched chains of Glucose. They have no interactions with other chains.

17

What does cellulose do in plants?

They are a structural Carbohydrate and are the structural component of plants. Only a slight difference to starch and have a dramatic difference in form and function.

18

What are lipids?

Very high energy stores. Contain 2 or 3 fatty acids and Glycerol.

19

What is the difference between liquid and solid lipids?

The number of double bonds(bends in tails) - more bends more liquid.

20

What are Biological membranes?

Phospholipids
– Glycerol + 2 fatty acids + phosphate group
• Makes up biological membranes
• Each molecule is a little AC/DC
• Each molecule has one end that hates water and
the other end that loves water (hydrophobic and hydrophilic)
• Result in a lipid bilayer
– Hydrophobic (water hating) tails together pointing in – Hydrophilic (water loving) heads together pointing out
• Result a membrane!

21

What do membranes do?

• Compartmentalize – keep things together or apart
• Store energy – act like a „hydro dam‟
• Hold onto things – proteins embedded
in membranes
• Selectively permeable- allow some things in keeps other things out

22

What are Amino acids and proteins?

• Amino acids are individuals (Monomer- subunits)
• Proteins are chains of amino acids • Function of Proteins
– Structural - building material for organisms
– Cytoskeleton – microtubles & actin filaments (see Unit 2.2)
– Enzymes – Special proteins that help in chemical reactions but are not part of the chemical reaction (biological catalysts)

23

What are Enzymes?

Enzymes ( biological catalysts)
• ALL enzymes are proteins
• NOT ALL proteins are enzymes

24

What happens in Biological reactions?

Most Biological Reactions:
• Will not occur spontaneously
• Activation energy (energy required to start the
reaction) is too high
• Must have enzymes to lower activation energy
• Enzymes therefore can be used as a means of controlling reactions
– No enzymes = no reaction
– Produce enzymes = reaction carried out

25

What are Nucleic acids?

Nucleic acids
• Store the “blueprint” for the metabolism and production of each cell.
• Each cell has an identical copy of DNA in every cell.
• RNA (Ribonucleic acid) – protein synthesis
• ATP – energy currency

26

Remember Nucleic acids

Adenosine Triphosphate (ATP) is a key form of nucleic acid. It does not incorporate into DNA or RNA but rather acts as an short term energy storage compound

27

DNA The double helix

Deoxyribose Sugar- Phosphate backbone- „sides of ladder‟
•Covalent bonds
•Complementary base pairing-
„rungs of ladder‟
•Purine pairs with a Pyrimidines via Hydrogen
bonds A-T G-C

28

What is Oxidation?

Oxidation:- removal of hydrogen, addition of O2.
Oxidation:- involves loss of electrons and energy.


29

What is Reduction?

Reduction:- addition of H+
Reduction:- involves gain of electrons and energy

30

Where do they occur?

Oxidation and reduction reactions always occur together! (REDOX Reactions)
If one molecule is reduced and gains e- then something must be oxidized and loses e-.
Oxidation and reduction reactions occur in photosynthesis and respiration
Energy is present in bonds of molecules like glucose
When H is removed H+ and e- (oxidation) energy is lost.
When H+ and e- are added (reduction) energy is gained
If one compound is oxidized the other is reduced. ENERGY changed not CREATED