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Biology > Chapter 3 > Flashcards

Chapter 3 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are the characteristics of water?

A 
High boiling point.
Ice is less dense than water.
Cohesive.
Adhesive.
Surface tension.
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2
Q

Why is water vital for life?

A 
Acts as a solvent.
Transport medium.
Coolant.
Stable.
Surface tension.
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3
Q

Which elements do carbohydrates contain?

A

Carbon, hydrogen and oxygen.

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4
Q

What is a monosaccharide?

A

A single sugar unit.

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5
Q

What is amylose?

A

A starch made of alpha glucose molecules joined only by 1-4 glycosidic bonds. The angle of the bonding means that the chain twists into a helix. Hydrogen bonding within the molecule stabilises it further.

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6
Q

What is amylopectin?

A

A starch made of alpha glucose molecules bonded by 1-4 glycosidic bonds. Some 1-6 branching points (approx every 25 glucose subunits).

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7
Q

What is glycogen?

A

Similar to amylopectin but forms more branches so it is more compact so less space needed to store it. This is important as animals move. Coiling and branching of glycogen makes it very compact and means that there are free ends where glucose molecules can be added or removed- speeds up storage and releasing process.

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8
Q

What is cellulose?

A

Made of beta glucose molecules bonded by 1-4 glycosidic bonds. Straight chained, no branches.
Cellulose make hydrogen bonds with each other, forming microfibrils which then join to make macrofibrils and then fibres. These are very strong and insoluble so are used to make cell walls.

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9
Q

How do you test for reducing sugars?

A

Place sample in a boiling tube. If it isn’t liquid, grind it up or blend with water.
Add equal volume of Benedict’s reagent which is an alkaline solution of copper(II) sulfate.
Heat the mixture in a boiling water bath for five minutes.
If there are reducing sugars, the solution should change from a blue colour to brick red.

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10
Q

How do you test for non reducing sugars?

A

Heat the sample with dilute hydrochloric acid then warm it with Benedict’s reagent.

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11
Q

How do you test for starch?

A

Iodine test:
Add a few drops of iodine dissolved in potassium iodide solution to the sample.
If starch is present, the solution should change colours from yellow/brown to purple/black.

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12
Q

What are quantitative methods to determine concentration?

A

Colorimetry and Biosensors

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13
Q

What is the significance of starch, glycogen and cellulose?

A

Starch- energy storage in plant cells only. Found inside chloroplast cell organelle (starch grains). STORAGE
Glycogen- energy storage in animal cells only. Found inside liver or exercising muscles. STORAGE
Cellulose- Makes plant cell wall. STRUCTURAL

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14
Q

What are the useful properties of glycogen and starch?

A

Compact, easily hydrolysed, does not alter water potential of cells and insoluble in water.

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15
Q

What is the function of cellulose?

A

Supports the plant cell.

Stop cells from bursting when animal cell moves in through osmosis.

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16
Q

Which elements do lipids contain?

A

Carbon, hydrogen and oxygen

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16
Q

What is a triglyceride?

A

A triglyceride is made by combining a glycerol molecule (which is an alcohol) and three fatty acids (which are carboxylic acids)

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17
Q

Which bonds are present in triglycerides?

A

Ester bonds.

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18
Q

Why are unsaturated fatty acids liquid?

A

The kink caused by the double bonds prevents the fatty acids from stacking on each other in a regular arrangement.

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19
Q

What is the significance of stored triglycerides?

A

ENERGY STORAGE- Able to be used in respiration to release energy (after hydrolysis).
INSULATION-in animals.
PROTECTION- stored around soft organs to absorb external shock and protect the organ.
BUOYANCY- Reduces density in aquatic animals, allowing them to float.
They give x2 the amount if energy (9kcal) than sugar (4.5kcal)

20
Q

What do phospholipids consist of?

A

Carbon, hydrogen, oxygen and phosphorus- 1 glycerol, 2 fatty acids and 1 phosphate

22
Q

Why are phospholipids called surface active agents/surfactants?

A

They form a layer on the surface of water with the phosphate heads in the water and the fatty acid tails sticking out of the water.

23
Q

What are the differences between saturated and unsaturated fats?

A

In the hydrocarbon tail of sats there is no double bond. In unsats, there are more than 1.
N.O. hydrogen atoms in sats is higher than in unsats.
Sats are solid at room temp and unsats are liquid.
Sats- more proportion of animal fats. Unsats- more proportion on plant fats.

24
Q

What are sterols?

A

Another type of lipids found in cells. They are complex alcohol molecules based on a four carbon ring structure with a hydroxyl group at one end which is hydrophilic. The rest of the molecule is hydrophilic.
An example is cholesterol.

25
Q

What are some of the roles of lipids?

A

Electrical Insulation
Waterproofing
Membrane formation
Hormone production

Roles of TRIGLYCERIDES:
Thermal insulation
Cushioning for vital organs
Buoyancy (for aquatic animals)

26
Q

What is the test for lipids?

A

Emulsion test:
Sample is first mixed with ethanol. The solution is then mixed with water and shaken. If a white emulsion forms as a layer on top, a lipid is present.

27
Q

What are proteins made up of?

A

Carbon, hydrogen, oxygen and nitrogen

They consist of an amine group, a R-group and a carboxyl group

28
Q

What type of bond is formed between amino acids?

A

Peptide bond

29
Q

What is the mobile and stationary phase of thin layer chromatography?

A

Mobile- solvent

Stationary- silica gel

30
Q

How is TLC used to separate amino acids?

A

A thin layer of silica gel is applied onto a rigid surface.
Amino acids are added to one end of the gel. This end is then submerged in organic solvent.
The organic solvent moves through the gel.
The rate at which the amino acids move through the silica gel depend in the interactions they have with the silica.

31
Q

What are the safety precautions to take when using TLC?

A

Wear safety goggles when working with chemicals and report any spillages/ breakages to the teacher.

32
Q

What are the different levels of protein structure?

A

Primary structure- peptide bonds
Secondary structure- hydrogen bonds
Tertiary structure- hydrogen bonds, ionic bonds, disulfide bonds and hydrophobic and hydrophilic interactions
Quaternary structure- same as tertiary structure

33
Q

Which enzyme is used to catalyse polypeptides?

A

Peptidyl transferase

34
Q

Which enzyme is used to hydrolyse proteins?

A

Protease

35
Q

How are globular proteins formed?

A

Hydrophobic R-groups go towards the inner side of the protein and hydrophilic R-groups stick outwards, forming a spherical shape. This means they are soluble.

36
Q

Give an example of and describe a globular protein.

A

Insulin- hormone involved in controlling blood glucose solution. Travels in blood so solubility is important. Binds to specific receptors so shape is important.

37
Q

What are conjugated proteins?

A

Types of globular proteins but with a non-protein component called a prosthetic group.

38
Q

Give two examples of conjugated proteins and describe them.

A

HAEMOGLOBIN- quaternary protein where each subunit contains a haem group. Iron II ions combine irreversibly with oxygen.

CATALASE- Enzyme containing four prosthetic haem groups. Iron II ions in prosthetic groups allow catalase to speed the breakdown of hydrogen peroxide, which is harmful to cells.

39
Q

What are Fibrous proteins?

A

Formed from long, insoluble molecules due to the many amino acids with hydrophobic R-groups in primary structure. Repetitive amino acid sequence in primary structure, leading to very organised structures. The proteins tend to make strong, long molecules that are jot folded into 3D shapes.

40
Q

Give and describe examples of fibrous proteins.

A

KERATIN- has sulfur containing AAs, cysteine hence strong disulfide bonds present. Degree if disulfide binds present determines flexibility.

ELASTIN- quaternary proteins made from tropoelastin. Very flexible. Fohnd in walls of blood vessels and in alveoli of lungs.

COLLAGEN- different forms all made up of three polypeptides wound together in a long and strong rope-like structure. Flexible. Is a connective tissue found in skin, tendons, ligaments and the nervous system.

41
Q

Which elements do nucleic acids contain?

A

carbon, hydrogen, oxygen, nitrogen and phosphorus

42
Q

What are the components that make up a nucleotide?

A

A pentose monosaccharide, a phosphate group and a nitrogenous base.

43
Q

What are the bonds linking nucleotides called?

A

Phosphodiester bonds.

44
Q

What are pyrimidines?

A

The smaller bases which contain single carbon ring structures. (thymine and cytosine)

45
Q

What are purines?

A

The larger bases which contain double carbon ring structures (adenine and guanine).

46
Q

What are the bonds between the strands of the DNA double helix called?

A

Hydrogen bonds.

47
Q

Why are there complementary base pairings?

A

Adenine and thymine only form two hydrogen bonds.

Cytosine and guanine only form three hydrogen bonds.

48
Q

What is the procedure for extracting DNA?

A

1) Grind the sample with a mortar and pestle. This will break down the cell walls
2) Mix with detergent- this will break down the cell membrane and releases cell contents into solution.
3) Add salt- this breaks hydrogen bonds between DNA and water molecules.
4) Add protease enzyme- this breaks down proteins associated with DNA in the nucleus.
5) Add layer of alcohol on top of the sample- causes DNA to precipitate out of solution.
The DNA will be seen the white strands forming between the sample and the alcohol.

Biology (11 decks)

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