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Biology Chapter 3 > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

What is a covalent bond?

A

When two non-metals cannot form a bond by transferring electrons from one to another. They share electrons to join atoms together. Called a covalent bond.

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2
Q

What are the functions of the useful biological ions?

A

Hydrogen ions- Catalysts, pH determination

Calcium ions- Nerve impulses, muscles, contractions

Sodium ions- Nerve impulses, kidney function

Potassium ions- Nerve impulses, stomata

Ammonium- To make nitrate ions

Nitrate- Amino acids and protein production

Hydrogen carbonate- Maintains blood pH

Chloride- Balance sodium and potassium ions in cells

Phosphate- Cell membranes
Nucleic acids and ATP formation
Bone formation

Hydroxide- Catalysts, pH determination

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3
Q

What elements are present in carbohydrates, lipids, proteins and nucleic acids?

A

Carbohydrates- carbon, hydrogen, oxygen

Lipids-carbon, hydrogen, oxygen

Proteins- carbon, hydrogen, oxygen, nitrogen, sulphur

Nucleic acids- carbon, hydrogen, oxygen, nitrogen, phosphorus

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4
Q

What is a monomer?

A

A single unit

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5
Q

What is a polymer?

A

Long chain molecules made by linking of multiple individual monomers, in a repeating pattern

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6
Q

What are covalent bonding in polar molecules?

A

Shared electrons in a covalent bond aren’t always equal

Electrons may spend more time around one atom than the other

Makes one atom slightly negative and one slightly positive

This is called polar

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7
Q

What type of molecule is water?

A

Covalent bonds between O & H
Oxygen shares more electrons and therefore slightly more negative
Hydrogen more positive
Positive and negative regions- polar molecules

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8
Q

The polarity of water

A

Polar molecules interact with each other

Form bonds called hydrogen bonds

Hydrogen bonds – Weak interaction which break and reform between water molecules

However – many bonds = stable/unique characteristics

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9
Q

What is hydrogen bonding?

A

Weak electrostatic bond.
Each bond is fairly weak, but together an important force.
Causes water molecules to stick together, giving unusual properties.

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10
Q

Unusual property one- Water has a high boiling point

A

It has a high specific heat capacity and is transparent, takes more energy to heat up than land does.

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11
Q

Unusual property two -Water is less dense when it freezes

A

Therefore ice floats, provides a surface of ice which insulates the water below and allows habitat for organisms and nutrients to flow through

This is because as water freezes the hydrogen bonds push the H2O molecules farther apart from each other increasing the intermolecular space resulting in expansion.

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12
Q

Unusual property three- water molecules stick together

A

Water molecules are attracted to each other:
Cohesion

Water molecules are attracted to other surfaces:
Adhesion

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13
Q

Unusual property 4- water is a good solvent

A

Molecules are polar

This enables water molecules to attract to solute molecules

This is important because it becomes a medium for metabolic reactions

Allows ionic compounds to separate
Allows a transport system
Eg Blood, xylem, tissue fluid

Dilutes toxic substances

Allows organisms to absorb gases

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14
Q

What are carbohydrates?

A

They are respiratory substrates.

These are substances that are broken down during respiration to release energy

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15
Q

What is a monosaccharide?

A

Single sugar unit with the general formula (CH2O)n, where n can be 3–7. eg C6H12O6
Eg- glucose, galactose, fructose

6 carbon sugar- hexose
5 carbon sugar- pentose

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16
Q

What is a disaccharide?

A

Formed from two monosaccharides by glycosidic bonds
Eg- lactose, sucrose, maltose

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17
Q

What is a polysaccharide?

A

Long chain carbohydrate polymers

Eg- glycogen , cellulose , starch

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18
Q

What is glucose?

A

Polar
Soluble in water due to the hydrogen bonds that form between the hydroxyl groups and water molecules.

This means that glucose is dissolved in the cytosol of the cell.

The major energy source for most cells.

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19
Q

What is galactose?

A

Respiratory substrate
Bonds contain energy

Can be broken down by enzymes

Soluble (transport)

OH/H can form H bonds with water

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20
Q

What happened when a disaccharide breaks down to monosaccharides?

A

Hydrolysis
Water breaks glycosidic bonds
Catalysed by enzymes

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21
Q

Where is maltose found?

A

Maltose (disaccharide) is found in germinating seeds as more complex carbohydrates are broken down for energy

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22
Q

Where is lactose found?

A

Lactose is found in mammalian milk to provide energy for infant mammals

Galactose & Glucose

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23
Q

Where is sucrose found?

A

Sucrose is transported in the phloem to provide sugars to other parts of the plant

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24
Q

What do the following disaccharides breaks down to?

A

Lactose- alpha glucose + beta galactose
Maltose- alpha glucose + alpha glucose
Sucrose- alpha glucose + alpha fructose

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25
Polysaccharides- starch
Many alpha glucose molecules can be joined by glycosidic bonds to form two slightly different polysaccharides known as starch. Overall structure of starch: - insoluble, branched, compact so ideal for their storage function - Insoluble means that it won’t affect the water potential
26
What is starch- amylose?
Long chain of a-glucose molecules joined by 1, 4 glycosidic bonds Amylose coils into a helix shape that makes it more compact (angle of bonding) Less soluble than glucose
27
What is starch amylopectin?
Long chain of a-glucose molecules joined by 1, 4 glycosidic bonds
28
Polysaccharides- glycogen
Storage molecules in animals and fungi Many 1,4 and 1,6 glycosidic bonds More branched than amylopectin
29
Glycogen
Storage molecule in animals and fungi Has both 1-4 glycosidic bonds and 1-6 glycosidic bonds Glycogen from more branches (every 8-12) than amylopectin which means it is more compact and ,less space needed for it to be stored Branches mean that there are many free ends where glucose molecules can be added or removed. Speeds up the process of storing or releasing glucose molecules required by cells.
30
Why do animals have glycogen but plants don’t?
Higher metabolic requirements More mobile and have muscles Nerves/organs
31
Polysaccharides- cellulose
Structural- cell walls Very strong and so stops cells bursting 1,4 glycosidic bonds Each B-glucose molecules must be inverted Inversions prevent cellulose from coiling and results in a long chain, straight chain Very hard to break down by hydrolysis Most animals lack cellulase to break down bonds Some herbivores have symbiotic bacteria in their guts that produce the enzyme.
32
What are lipids?
Macromolecule Non-polar
33
How to make a triglyceride?
The hydroxyl groups interact, leading to the formation of three water molecules and bonds between the fatty acids and the glycerol molecule. Condensation reaction called esterification (formation of ester bonds).
34
How to break a triglyceride?
Hydrolysis reaction with the addition of three water molecules.
35
What does it mean to be saturated?
C-C single bonds Straight chain Saturated with H atoms (all C atoms are bonded to max no. of H atoms) Fats
36
What does it mean to be unsaturated?
C=C double bonds Mono or polyunsaturated Bent chain (atoms not packed as closely together) Oils
37
What is the difference between structure of a triglyceride and phospholipids?
One of the fatty acid chains has been replaced by a phosphate group. It is an inorganic phosphate ion (PO43-). The phosphate group is ionised (negatively charged) as it has extra electrons.
38
What are sterols?
A type of lipid found in cells 4 carbon rings with a hydroxyl group at one end Hydrophilic/hydrophobic The hydroxyl group is polar – and hydrophilic The rest of the molecule is hydrophobic Examples Cholesterol: Used in cell structure Testosterone/Oestrogen: Hormones
39
What is cholesterol?
Manufactured in the liver and intestines Forms cell membranes Adds stability and fluidity Fluid at low temperatures Not too fluid at high temperatures
40
What does cholesterol do to phospholipids?
Cholesterol bonds to the fatty acids tails of phospholipids. Hydrophilic hydroxyl (-OH) group aligns towards the phosphate heads of phospholipids. Remainder of the molecule (steroid ring and hydrocarbon tail) is hydrophobic and binds to the phospholipid tails.
41
How does cholesterol moderate properties of the membrane?
It immobilise outer surface of the membrane, reducing fluidity and adding stability. Stops membrane from being too fluid at high temperature, but fluid at low Makes membrane less permeable to very small water-soluble molecules that would otherwise freely cross.
42
What are the role of lipids?
Membrane formation Hormone production Electrical insulation – Impulse transmission Waterproofing (birds feathers, Plant leaves Mainly triglycerides Thermal insulation (eg Penguins) Cushioning to protect vital organs (Eg heart) Buoyancy for aquatic animals (eg Whales)
43
How does the synthesis of proteins work?
Amino acids join when amine and carboxylic acids groups connect to central carbon atom reacts. Hydroxyl in carboxylic acid group of one amino acid reacts with a hydrogen in amine group in another amino acid. Peptide bond is formed between the amino acids and water is produced. The compound will be dipeptide. When many amino acids are joined together by peptide bonds a polypeptide is formed.
44
What is the primary structure of proteins?
Primary structure of a protein is the order and number of amino acids in a protein. Polypeptide bonds only.
45
What is the secondary structure of proteins?
The secondary structure is the shape that the chain of amino acids takes. Shape determined by the hydrogen bonding.
46
What is the tertiary structure of proteins?
It is the 3D shape of the protein. It can be globular or fibrous. R groups are closer together and so form bonds: Hydrophobic/hydrophilic Hydrogen bonds Ionic bonds Disulphide bonds
47
What are the possible interactions in tertiary structure?
Hydrogen bonds- weakest bonds Hydrophobic and hydrophilic interactions- weak interactions between polar and non-polar R-groups Hydrophobic groups are on the inside Hydrophilic are on the inside of the molecule Ionic bonds- Stronger than hydrogen bonds and form between oppositely charged R-groups Disulfide bonds- Covalent are the strongest bonds Only occur between R-groups that contain sulfur
48
What is the quaternary structure of proteins?
Association of 2 or more individual proteins called alpha, beta subunits.
49
What are the 2 types of proteins?
Globular and fibrous
50
What are the properties of globular proteins?
3D Compact Soluble Hydrophobic R groups fold inwards Roughly spherical
51
What are the properties of fibrous proteins?
Long Insoluble High no of hydrophobic R groups Organised structure Strong Not folded into 3D shapes
52
What are the two types of proteins based on composition?
Simple Conjugated- contains non protein group Has prosthetic group Prosthetic group attached by covalent bonds
53
Type of protein - insulin
Globular Hormone that regulates blood sugar Standard globular
54
Type of protein- elastin
Fibrous Wall of blood vessels and alveoli Quaternary protein made of tropoelastin Very large, stable and insoluble
55
Type of protein- haemoglobin
Conjugated Carries oxygen in red blood cells Globular quaternary structure 2 alpha+ 2 beta subunits Each contain haem prosthetic group
56
Type of protein- collagen
Fibrous Connective tissue 3 polypeptide chains wound round each other triple helix. Rope like structure, held with h bonds Every third amino acid is glycine
57
Type of protein- keratin
Fibrous Found in hair and nails Large proportion of cysteine forming lots of strong disulphide bridges
58
Type of proteins - catalase
Conjugated Catalases breakdown of hydrogen peroxide Globular quaternary protein with four haem groups
59
What is the synthesis of nuclei acids?
Linked by condensation reactions to form a polymer called polynucleotide. Phosphate group at fifth carbon of pentose sugar of pentose sugar of one nucleotide forms a covalent bond with hydroxyl group at third carbon of pentose sugar of an adjacent nucleotide. This is called a phosphodiester bond. Forms a long strong sugar phosphate backbone with a base attached to each sugar. The phosphodiester bonds are broken by hydrolysis.
60
DNA
Deoxyribonucleic acid Double helix Two parallel strands run antiparallel
61
What is RNA
Plays an essential role in the transfer of genetic information from DNA to the proteins that make up the enzymes and tissues in the body. This is because DNA is a very long molecule and cannot leave nucleus. Pentose sugar is ribose. Thymine base is replaced with uracil which form 2 hydrogen bonds with adenine. Phosphodiester bonds in condensation reaction.
62
What is DNA replication and why is it important?
It is making identical copies of DNA. It is important because for cell division as new cells need DNA for growth and tissues repair. It is also important for reproduction as gametes require DNA to pass on genetic information.
63
What is the process of DNA replication?
1) DNA starts to separate. DNA helicase breaks the hydrogen bonds between the two strands. 2)free nucleotides are attracted to their ‘unpaired’ complementary base pair 3)as free nucleotides pair up with original DNA strand DNA polymerase catalyses the formation of phosphodiester bonds between nucleotides. 4) eventually DNA polymerase joins all of the nucleotides to form a complete nucleotide chain. Two identical molecules of DNA are formed Each molecule has one original strand, and one newly formed molecule. This is semi conservative replication.
64
What are replication errors?
Bases are not always matched exactly Sometimes randomly there are errors which change the sequence. This is a mutation.
65
What is genetic code?
Sequences of bases in DNA are the instructions for the sequences of amino acids in the production of proteins All organisms have the same code. It’s non-overlapping the triplets don’t run over each other.
66
The genetic code
4 bases Codons made or 3 bases 64 different codons 20 different amino acids Genetic code explains how each base combinations makes the different amino acids
67
What is the degenerative code?
It is when more than one codon codes for one amino acid
68
What are the two stages of protein synthesis?
Transcription- DNA to mRNA leaving nucleus Translation- mRNA- binds with ribosomes, tRNA carrying an amino acids, builds up polypeptide chain.
69
How does transcription work?
DNA can’t leave nucleus 1) DNA double helix unzips with DNA helicase 2) Free RNA nucleotides bind to complimentary bases along the DNA 3) RNA polymerase forms the phosphodiester bonds between the RNA nucleotides forming a strand of messenger RNA 4)mRNA then leaves the nucleus through a nuclear pore.
70
How does translation work?
1) mRNA binds to the ribosome 2) tRNA bond to mRNA 3) anticodon pair with codons 4) specific amino acids attached to tRNA 5) formation of peptide bond between amino acids
71
ATP stand for
Adenosine triphosphate
72
How ATP releases energy?
Energy is needed to break bonds Hydrolysis of the terminal phosphate group by Atpase releases 30.5kJ/mol of free energy
73
Hydrolysis of ATP to adp
ATP + H2O ————-> ADP+ Pi + energy
74
Unstable phosphate bonds
Not a long term energy store Energy released in the breakdown Phosphorylation
75
Properties of ATP
Releases a small amount of energy at a time Water soluble Small- moved easily into out of cells Easily regenerated Releases energy instantaneously- always available

Biology Chapter 3 (1 decks)

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