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PROTEINS Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Just like carbohydrates, proteins are ______

A

Polymers

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2
Q

Amino acids are _____ in proteins

A

Monomers

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3
Q

What makes a dipeptide?

A

A DIPEPTIDE is formed when TWO amino acids join together.

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4
Q

What makes a polypeptide?

A

A POLYPEPTIDE is formed when MORE THAN TWO amino acids join together.

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5
Q

What makes a protein?

A

PROTEINS are made of ONE OR MORE POLYPEPTIDES

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6
Q

What is an amino acid general structure?

A

A carboxyl group (-COOH) and an amine group (-NH3) attached to a carbon atom with a variable group R.

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7
Q

All amino acids contain what chemical elements?

A

carbon, oxygen, hydrogen, nitrogen and some contain sulfur.

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8
Q

What bond holds amino acids together?

A

Amino acids are linked together by PEPTIDE BONDS to form dipeptides and polypeptides

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9
Q

A molecule of WATER is RELEASED during the reaction- it’s a _______ reaction

A

condensation

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10
Q

The reverse of a condensation reaction is adding a molecule of water to BREAK the peptide bond-it’s a ______ reaction

A

hydrolysis

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11
Q

What is the PRIMARY structure of amino acids?

A

This is the SEQUENCE of AMINO ACIDS in the POLYPEPTIDE CHAIN.

Different proteins have DIFFERENT SEQUENCES of amino acids in their primary structure

A change in just one amino acid may change the structure of the whole protein.

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12
Q

what is the SECONDARY structure of amino acids?

A

The polypeptide chain doesn’t remain flat and straight.

HYDROGEN BONDS form between nearby amino acid in the straight chain.

This makes it automatically COIL into an ALPHA (a) HELIX or FOLD is a BETA(B) PLEATED SHEET-this is the secondary structure.

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13
Q

What is the TERTIARY structure of amino acids?:

A

The coiled or folded chain of amino acids is often COILED or FOLDED FURTHER.

MORE BONDS form between different parts of the polypeptide chain.

For proteins made from a SINGLE polypeptide chain, the tertiary structure forms their final 3D STRUCTURE.

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14
Q

What is the QUATERNARY STRUCTURE of amino acids?

A

Some proteins are made of SEVERAL DIFFERENT POLYPEPTIDE CHAINS held together BY bonds.

The QUATERNARY STRUCTURE is the way these polypeptide chains are assembled together

E.G. HAEMOGLOBIN is made of four polypeptide chains, bonded together.

For proteins made from MORE THAN ONE polypeptide chain, the quaternary structure is the proteins FINAL 3D STRUCTURE.

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15
Q

COMPUTER MODELLING can create _____ of proteins

A

3D interactive images

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16
Q

This is really handy for INVESTIGATING the ______ in a protein molecule.

A

different level of structure

17
Q

What bond(s) hold the primary structure?

A

Held together by the PEPTIDE BONDS between amino acids.

18
Q

What bond(s) hold the secondary structure?

A

Held together by HYDROGEN BONDS?

19
Q

What bond(s) hold the tertiary structure?

A

Held together by Ionic bonds, Disulphide bonds, Hydrophobic and hydrophilic interactions and Hydrogen bonds.

20
Q

What is an ionic bond?

A

These are attraction between NEGATIVELY-CHARGED R groups and POSITIVELY-CHARGED R groups on different parts of the molecule.

21
Q

What is a Disulphide bond?

A

Whenever two molecules of the amino acid CYSTEINE come close together, the SULFUR ATOM in one cysteine bonds to the sulfur atom in the other cysteine, forming a disulphide bond.

22
Q

What are hydrophobic and hydrophilic interactions?

A

When HYDROPHOBIC (water-repelling) R groups are close together in the protein, they tend to CLUMP TOGETHER.

This means that Hydrophilic (water-attracting) R groups are more likely to be pushed to the outside, which affects how the protein FOLDS UP into its final structure.

23
Q

What are hydrogen bonds?

A

These weak bonds form between POSITIVELY CHARGED HYDROGEN ATOMS in some R groups and SLIGHTLY NEGATIVELY-CHARGED atoms in other R groups on the polypeptide chain

24
Q

What bonds hold the Quaternary structure?

A

This tends to be determined by the TERTIARY STRUCTURE of the individual polypeptide chains being bonded together

25
Q

What happens when you heat a protein to very high temperatures?

A

Heating a protein to a HIGH TEMPERATURE will break up its ionic and hydrophobic/hydrophilic bonds interactions and hydrogen bonds. In turn, it will cause a change in the proteins 3D shape.

26
Q

Why are globular proteins round?

A

In a globular protein, the HYDROPHOBIC R GROUPS on the amino acids tend to be pushed to the OUTSIDE of the molecule.
This caused by the HYDROPHOBIC and HYDROPHILIC INTERACTIONS in the proteins tertiary structure.

27
Q

(Globular protein) Having hydrophobic r groups outside the molecule makes the protein ______

A

Soluble, so they are EASILY TRANSPORTED in fluids.

28
Q

Globular proteins have a range of functions in living organisms such as Haemoglobin. What is Haemoglobin?

A

Haemoglobin is a globular protein that carries OXYGEN around the body in RED BLOOD CELLS.

It’s known as a CONJUGATED PROTEIN this means its a protein with a NON-PROTEIN GROUP attached.

The non-protein part is called a PROSTHETIC GROUP.

Each of the four polypeptide chains in haemoglobin has a prosthetic group called HEAM.

A heam group contains IRON, which oxygen binds too.

29
Q

Globular proteins have a range of functions in living organisms such as Insulin. What is Insulin?

A

Insulin is a hormone secreted by the PANCREAS.

It helps to regulate the BLOOD GLUCOSE LEVEL.

Its SOLUBILITY is important-it means it can be TRANSPORTED in the BLOOD to the tissues where it acts.

An insulin molecule consists of two POLYPEPTIDE CHAINS, which are held together by DISULPHIDE BONDS.

30
Q

Globular proteins have a range of functions in living organisms such as Amylase. What is Amylase?

A

Amylase is an ENZYME that catalyses the breakdown of starch in the digestive system.

It is made of a SINGLE CHAIN of amino acids.

Its secondary structure contains BOTH alpha-helix and beta-pleated sheets sections.

MOSTNZYMES are GLOBULAR PROTEINS.

31
Q

What are Fibrous proteins?

A

Fibrous proteins are INSOLUBLE and STRONG.

They’re STRUCTURAL proteins and are fairly unreactive (unlike many globular proteins).

32
Q

Fibrous protein is TOUGH and ROPED SHAPED, such as collagen. What is collagen?

A

Collagen is found in animal CONNECTIVE TISSUES, such as bone, skin and muscle.

It is a very STRONG molecule.

MINERALS can bind to the protein to increase its RIGIDITY, e.g in the bone.

33
Q

Fibrous protein is TOUGH and ROPED SHAPED, such as Keratin. What is Keratin?

A

Keratin is found in many of the EXTERNAL STRUCTURES of animals, such as skin, hair, nails, feathers and horns.

It can either be FLEXIBLE (as it is in the skin) or HARD AND TOUGH (as it is in nails)

34
Q

Fibrous protein is TOUGH and ROPED SHAPED, such as Elastin. What is Elastin?

A

Elastin found in ELASTIC CONNECTIVE TISSUE, such as skin, large blood vessels and some ligaments.

It is Elastic, so it allows tissues to return to its original shape after it has been stretched.

35
Q

Describe the general structure for an Amino acid.

A

Amino group(NH2) attached to a carbon with a hydrogen and variable R group. Carbon attached to a Carbonyl group(-COOH)

36
Q

Name the bonds that join amino acids together in proteins.

A

Peptide bonds

37
Q

What is a conjugated protein?

A

Conjugated protein means its a protein with NON-PROTEIN GROUP attached.

The non-protein protein part is called a PROSTHETIC GROUP.

38
Q

Suggest which of the following proteins is most abundant in a tortoises shell
Collagen, Elastin, Alpha-amylase, Keratin

A

Keratin

39
Q

HSA is a globular protein, which transports other molecules such as fatty acids around the bloodstream. The molecule consists of 585 amino acids, several of which are cysteine.
Describe the bonds that could be present in the tertiary structure of HSA and suggest how its structure makes it suited for its role of transporting molecules in the blood.

A

The tertiary structure may contain IONIC BONDS.
These are attractions between negatively charged R-groups and positively charged R-groups on different parts of the molecule.

It may also contain DISULPHIDE BOND, which forms when the sulfur atom in two nearby cysteine molecules bond.

There may also be hydrogen bonds, which are weak bonds between slightly positively charged hydrogen atoms in some R groups, and slightly negatively charged atoms in other R groups in the polypeptide chain.

The tertiary structure will also contain Hydrophobic and Hydrophilic interaction.
Hydrophobic R groups clump together, meaning the hydrophilic R groups are more likely to be pushed to the outside

This will make HSA SOLUBLE in water, which makes it suited for transporting molecules in the blood.

Biology (18 decks)

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