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bio as > ch 2: biological molecules > Flashcards

ch 2: biological molecules Flashcards

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Biology 101 flashcards
1
Q

monosacch

A

formula: (CH2O)n
-trioses intermediate to respiration and photosynthesis
-pentoses
°ribose for DNA and ATP
°deoxyribose for DNA
-hexoses as glucose, fructose they are used in respiration and energy release and in the formation of di/poly-sachh

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2
Q

properties of monosacch

A

all are reducing sugars
they have a reactive group to reduce benedict.
all are water soluble
polar, so water molecules can cluster around them and hydrogen bond with them

-sweet
-crystalline
-formed of one carbon ring

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3
Q

polysacch

A

-starch
-glycogen
-cellulose
-chitin
-starch and glycogen has metabolic functions.
they can be stored as they are not reactive and soluble
-cellulose has a structural function.it enters in the formation of cell wall as it has a high tensile strength

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3
Q

properties of disacch

A

maltose and lactose are reducing sugars while sucrose is non reducing sugar (why?)

-all are water soluble but less soluble than monosachh
-sweet
-crystalline
-formed of 2 carbon rings

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3
Q

disachh

A

formula C12 H22 O11
-sucrose
-lactose
-maltose

-sucrose is translocated in the phloem as it is less reactive than glucose and more soluble than starch

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4
Q

properties of polysacch

A

all non reducing sugars
water insoluble
-not sweet
-not crystalline
-formed of more than 2 carbon rings

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5
Q

how a-glucose differs from B-glucose (2marks)

A

a-glucose has its -OH group of carbon atom number one pointing downwards while that of B-glucose has the OH group pointing upwards

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6
Q

breakage of glycosidic bond

A

it occurs as a result of hydrolysis reaction which involves
-the addition of water
- the transformation of large mol into smaller
-it is controlled by specific enzymes

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7
Q

formation of glycosidic bond

A

it occurs as a result of condensation reaction while involves:
-the removal of water
-the transformation of monomers into larger mol
it i controlled by specific enzymes

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8
Q

why sucrose is non reducing sugar?

A

-doesn’t react with benedict to give brick-red colour
-it doesn’t have a reactive group to reduce benedict
-needs to be boiled with dilute HCL to breakdown glycosidic bond

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9
Q

starch has 2 forms

A

amylose and amylopectin

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10
Q

describe the structure of amylose and how it relate to it function

A

it is a polymer of a-glucose
linked by 1,4 glycosidic bond
it is non branching and takes a helical shape
-most of their OH group pointing inward

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11
Q

structure of amylopectin and how it relate to its function

A

polymer of a-glucose
linked by 1,4 glycosidic and 1,6 glycosidic bonds
not helical
-branching
this structure makes the amylopectin and glycogen insoluble, compact & easily hydrolyzed. by this amylopectin and glycogen have a metabolic function as they are convenient energy storage molecules.

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11
Q

what makes amylose convenient storage molecule

A

-insoluble: so will not lower the water potential and will not change the osmotic pressure inside the cell. it will affect on the chemical reaction inside the cell
-compact: so will take small room inside the cell
easily hydrolyzed by specific enzymes, to give glucose for respiration and energy release

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12
Q

why is it an adv for animal cell to store glycogen not amylopectin

A

glycogen is more branching so has more free ends for enzymes to work, so more glucose produced by unit time for more respiration also more glucose added

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13
Q

describe glycogen and how it relate to it function

A

glycogen is similar to amylopectin but more branching

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14
Q

what makes cellulose mol flat ribbon?

A

the OH group on carbon atom one is pointing upwards and the OH group of carbon number 4 is pointing downwards- to form 1,4 glycosidic bond, one glucose mol has to turn up side down relative to the other, that is rotated 180°

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15
Q

describe cellulose structure and how it relate to it function

A

-cellulose is a polysacch
-it is a polymer of B-glucose
-linked by B-1,4 glycosidic bond
-straight chains and not branching
-cellulose molecule are arranged parallel to each other.

-so OH group pointing in all directions so many hydrogen bonds form between cellulose molecules to form bundles of microfibrils, that cross link together with many hydrogen bonds to form cellulose fibers.

-this gives an extremely strong,insoluble,and slightly elastic structure that enters in the formation of cell wall as it has high tensile strength to withstand high turgor pressure inside the cell.

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16
Q

lipids forms

A

-triglycerides
-phospholipids
-cholesterol
elements: C H O
-proportion of the oxygen is much reduced in lipids that carbohydrates

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16
Q

triglycerides structure

A

glycerol & 3 fatty acid tails
triglycerides differ from each other according to no of CH2 in hydrocarbon chain that make tail vary in length

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17
Q

what makes cellulose have a high tensile strength that makes the it enter formation of the cell wall

A

many hydrogen bonds between cellulose mol to formation microfibrils
many hydrogen bonds between the bundles of microfibrils to form fibers

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18
Q

difference between saturated fatty acids and unsaturated fatty acids

A

-unsaturated fatty acid does not contain the max no of hydrogen atoms
-unsaturated fatty acids contains one or more double bonds between carbon atoms in hydrocarbon chain
-unsaturated fatty acid forms a kink

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18
Q

properties of triglycerides

A

-nolar as they have hydrophobic head and three hydrophobic tails
-head is made of glycerol and tail is made of three fatty acid tails
-some triglycerides are solid at room temp as they are formed of saturated fatty acids, others are liquid at room temp. formed of unsaturated fatty acids.
-less dense than water so can float

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19
Q

relate the structure of triglyceride to its function

A

*hydrophobic: it can be stored in body, protects delicate organs

*non polar: it acts as a thermal insulator, found under the skin, and electrical insulator so enters in the formation of myelin sheath

*stores energy; it releases more than twice the energy released by the same mass of carbohydrates as it has many C-H bonds, highly reduced and has many hydrogen atoms

*respiration: of desert animals, such as camel, to release metabolic water

19
Q

structure phospholipids

A

phospholipid molecule has a head made of glycerol and phosphate and two fatty acids tail

20
Q

properties of phospholipids

A

they have a hydrophilic head made of glycerol and phosphate, two hydrophobic fatty acids

21
Q

relate the structure of cholesterol to its function

A

-cholesterol enters in the formation of the cell membrane
-cholesterol regulates fluidity cell membrane
-maintains cell membrane mechanical stability
-synthesis of hormones

22
Q

steroids and cholesterol

A

skeleton of cholesterol is a set of complex rings of carbon atoms. The bulk of the molecule is hydrophobic but each molecule has at one end an OH group ? this makes this small part of cholesterol hydrophilic

22
Q

relate the structure of phospholipids its function

A

phospholipid molecules have hydrophilic head that can face water in cytoplasm and tissue fluid and hydrogen bonds with water molecules, and hydrophobic tails that repel water, this makes phospholipid molecule arrange themselves tail to tail to form phospholipid bilayer with hydrophobic core, that forms the basic structure of the cell membrane

23
Q

proteins structure

A

proteins are macromolecules
elements in proteins C H O N
monomers are amino acids
there are 20 different amino acids

24
Q

each amino acids formed of

A

amine group
R groups
carboxyl group
centeral carbon knows as a-carbon

25
Q

imprtance of R-group

A

interactions between R groups maintain the three dimensional shape of protein.
it determines if the protein is water soluble when it has the hydrophilic R groups pointing outward and hydrophobic R-groups pointing inward

act as abuffer

26
Q

function of amino acids

A

buffer:
=m they maintain the concentration of H ions in the solution.
- if the ph decreases ,then the amine group takes H ions, if the PH increases the carboxyl group gives H ions.

they are used to build up dipeptides,polypeptides and protein: the amino acids join together by a pepetide bond formed due to condesation reaction

27
Q

quaternary structure (HB and antibodies)

A

more than one polypeptide chain. held by interactions between R-groups
-hydrogen bonds
-ionic bonds
-disulfide bonds
-hydrophobic interactions

27
Q

primary structure

A

sequence of amino acids in polypepetide chain held together by peptide bonds.
specific sequence of R-groups determines pattern of protein folding

28
Q

secondary structure

A

folding of polypeptide chain to form :
-a-helix
-B-pleated sheet

in a-helix each N-H forms hydrogen bond with C=O three or four amino acids apart in same polypepetide

in b-pleated sheet each N-H forms hydrogen bond with C=O on adjacent part of the polypeptide

29
Q

tertiary structure

A

folding n coiling of polypeptide chain to form a specific 3D-shape.this is determined by sequence of amino acids in polypeptide chain.
held by interactions between R-groups:
-hydrogen bonds
-ionic bonds
-disulfide bonds
-hydrophobic interactions

30
Q

peptide bond

A

makes- primary structure
two amino acids can join together
one loses a hydroxyl (-OH) group form its carboxylic acid group, while the other loses a hydrogen atom from its amine group

by condensation reaction removing water
carbon of carboxyl group from first amino acid bonds to nitrogen of amine group from the second amino acid

31
Q

hydrogen bonds

A

between NH group of amino acid and C=O of another amino acid
broken down by high temp

makes 2ry,3ry,4ry

32
Q

ionic bonds

A

forms between ionised amine groups and ionised carboxyl Rgroups. they can be broken PH changes
makes 3ry,4ry

33
Q

Disulphide bonds:

A

Form between S in R-groups of cysteine molecules. * They are strong covalent bonds “not broken by high temp or pH change” * They can be broken by reducing agents makes 3ry and 4ry

34
Q

hydrophobic interactions

A

forms between non polar R groups of amino acids
weak bond
non polar R-groups tend to stay together because they are repelled by the watery environment around them

35
Q

Account for the importance of hydrophobic interaction?

A

It holds protein molecules in the cell membrane It holds cholesterol molecules In the cell membrane It maintains the three dimensional shape,

36
Q

types of proteins

A

Globular protein:
Ball shaped
Water-soluble
Hydrophilic R-groups pointing outwards & Hydrogen bond with water molecules, hydrophobic R=groups pointing Inwards.
Tertiary structure
Metabolic functions; as enzymes, hormones, antibodies, & Hb.

fibrous protein:
-parallel ropes
-insoluble
-structural role as collagen in skin

37
Q

Explain the adaptation of red blood cell to carry oxygen:

A

-They are biconcave disc -> to increase the surface area to absorb more oxygen.
-they have hemoglobin -> to combine with oxygen giving oxyhemoglobin
-they have no nucleus->to give more space to carry more hb
-they are very small and can squeeze themselves in the fine blood capillaries.

38
Q

Molecular structure of hemoglobin and its adaptations:

A

Globular protein - > ball shape, water soluble + Why? Has a quaternary structure -> 4 polyp, chains. 2 a globin chains & 2 B globin chains.
Each polyp. chain has a haem group made of iron to combine with one oxygen forming oxyhemoglobin.
Hb + 4O2 - > HbO8
Each hemoglobin molecule will combine with four oxygen molecules (8 oxygen atom

39
Q

Molecular structure of collagen

A

-It is an insoluble fibrous protein
-It is made of three polypeptide chains (each takes a helical shape), forming a triple helix.
- Each third amino acid is the smallest amino acid glycine, so the three strands are tightly coiled.
-The three polypeptide chains are held by many hydrogen bonds.
-Each three stranded collagen molecule interacts with another collagen molecules parallel to it by covalent bonds between the R groups of amino acids forming collagen fiber.
-The ends of the parallel molecules are staggered to avoid any weak point.
- Collagen has a high tensile strength.

40
Q

Function of collagen

A

High tensile strength Enters in formation of bones, tendons, & ligaments.

41
Q

Properties of water molecule

A

Water is a solvent: Water is dipolar. It clusters around polar molecules & ions, & hydrogen bond with them separating them from each other and allowing them to move freely and independently.

42
Q

Why water important?

A

Allow metabolic reactions as solutes are moving freely, so able to react. Transport medium: .
In animals: water allows transport of digested food, wastes, hormones, salts, antibodies in blood & lymph

In plants: salts transported in xylem, sucrose & AAs translocated in phloem. water maintain the stability of the cell membrane by making hydrogen bonds with hydrophilic heads of phospholipid bilayer.

43
Q

how does Water has a high latent heat of vaporization:

A

water molecules stick to each other by many hydrogen bonds, so large amounts of energy are needed for hydrogen to break down for evaporation

44
Q

why is it important that water has high latent heat of vaporization

A

Thermostability (keeping body temperature constant ) as it is used to cool animals as water absorbs a large amount of heat energy to evaporate as sweat. It cools down plant by transpiration.

45
Q

how water has a high specific heat capacity?

A

The amount of heat required to raise temperature of 1Kg of water by 1C Water has a high specific heat capacity as it absorbs a lot of heat energy without showing increase in temperature, due to many Hydrogen bonds between water molecules.

46
Q

why is it important that water has a high specific heat capacity

A

Provides stable environment for aquatic organisms. * keeps optimum temperature for enzymes. as in cells, as bodies are composed mainly of water (70- 80% ), so absorb heat without increasing in temperature.

47
Q

Water has a high surface tension, Cohesion & Adhesion forces.

A

Cohesion: force by which water molecules stick together by hydrogen bonds.
High Surface tension: High cohesion results in high surface tension at the surface of water.
Adhesion forces: water molecules stick to other molecules, as hydrophilic part of cellulose cell wall in xylem.

48
Q

why is it important that Water has a high surface tension, Cohesion & Adhesion forces.

A

High surface tension; allows small organisms, such as pond skaters, to use the surface of water as a habitat.
Cohesion: Allows mass flow in xylem and phloem (sieve tube), as water molecules stick together by many hydrogen bonds so move in long, unbroken columns.

49
Q

freezing properties of water

A

when temp falls below 4°C the volume of water increases & the density of water decreases, this makes the solid form,ice,less dense than water

50
Q

why freezing water is important

A

ice floats on water, acts as an insulator.
“protects aquatic org living below from being frozen”
mineral nutrients are bought to the surface: as frozen lake warms after the cold winter

51
Q

other imp of water

A

-activating enzymes,supportibg plant by making the cells turgid, photosynthesis , in hydrolysis
-water is transparent to allow light to penetrate and be absorbed by the plant & allow fish to see.

bio as (9 decks)

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