Unit 6: General Biochemistry Flashcards by Elif Naz Birant

B1.1.1

What are the chemical properties of a carbon atom?
Why is it so important?
What is a covalent bond?

Carbon can form 4 stable covalent bonds with many different types of atoms
Creating stable/complex structures and molecules.

Covalent bond: a bond created by the sharing of electrons between two atoms

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B1.1.2

What is a condensation reaction?
What is a glycosidic bond?

A reaction that removes water to form a bond between two molecules and requires energy.

Condensation reactions: remove water to form a bond between two molecules
- Requires energy
- If it is a bond between two monosaccharides (simple sugars) it is a glycosidic bond

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B1.1.2

What are disaccharides?

Two monosaccharides bonded together, such as maltose.

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B1.1.2

Define polysaccharide.

Many monosaccharides bonded together, for example, amylopectin.

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B1.1.2

What are 1-4 and 1-6 linkages in carbohydrates?

1-4 linkages → linear (n1 car – n4 carbon) (e.g. maltose)
1-6 linkages → branched (amylopectin)

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B1.1.2

What are the two forms of glucose?
How do you draw them?

Alpha glucose and Beta glucose.

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B1.1.3

What is digestion in the context of polymers?
Hydrolysis?

The chemical breakdown of larger molecules into small molecules, typically by hydrolysis.

Hydrolysis: Adding water to break the bonds of polymers

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B1.1.4

What is a monosaccharide?
What are the types of monosaccharides?

Monosaccharide: simple sugar
- Triose : 3 carbon sugars
- Pentose : 5 carbon sugars : ribose, deoxyribose
- Hexose: 6 carbon sugars

5C and 6C forms ring with an oxygen atom

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B1.1.4

What is the most important monosaccharide? Why

Most important monosaccharide → Glucose: C6H12O6
- Soluble in water (polar)
- Small
- Stable
- Produces energy when oxidized (cell respiration)

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B1.1.5

What are polysaccharides?
What are their general features?
What are their different functions?

Polysaccharides: Many monosaccharides bonded together

They are all:
- Not soluble (implications in transportation, osmolarity)
- No fixed size

But might have different in functions:
- Structural support → Cellulose in cell walls of the plants
- Energy storage → Glycogen (in animals) and starch (in plants)

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B1.1.6

What is cellulose?

Cellulose: Structural component in plants’ cell walls
- B-glucose with **1-4 **glycosidic bonds, linear

Explanation: Since glucose molecules are polar they have partially negative and positive poles and when they are parallel to each other they can form hydrogen bonds that hold the chains together
So it is very strong → it’s a structural component

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B1.1.7

What role do glycoproteins play?

Glycoprotein: Polypeptide with attached carbohydrate chain
- On the cell membrane with chains facing outwards
- Outside of the cell, the carbohydrate chain is used for the cell-to-cell recognition
- Cells approach and then glycoproteins recognizes

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B1.1.8

What are the hydrophobic properties of lipids?
Types of lipids?

All lipids are hydrophobic
- Non-polar, non-soluble in water

Types: Fats, oils, waxes and steroids

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B1.1.9

What are fatty acids?
What molecules can we form?

Fatty acid
Carbon chains, with hydrogens attached to them.
Methyl group (CH3) - Carbon chain – Carboxyl group (COOH)

We can make a triglyceride or phospholipids through condensation reactions
- Triglyceride: glycerol + 3 fatty acid chains
- Phospholipid: glycerol + 2 fatty acids + phosphate group

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B1.1.10

What is the difference between saturated and monounsaturated and polyunsaturated fatty acids?

Fatty acid types: aren’t identical, can come in several different forms
- Saturated
- Monounsaturated
- Polyunsaturated

Saturated fatty acids
- Have single bonds
- Straight
- Are solid at room temperature
- E.g. butter and margarine

Monounsaturated fatty acids
- Contain one double bond (bending the chain)
- Are liquid at room temperature.

Polyunsaturated fatty acids
- Contain more than one double bond between 2 carbons (multiple bendings)
Has two types
- Cis-unsaturated fatty acids
- Trans-unsaturated fatty acids

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B1.1.11

What is the role of adipose tissue?

Adipose tissue
- Stores energy as **triglycerides **under the skin and around organs
- Provides thermal insulation, not good heat conductors, so they help keep organisms warm
- Are good shock absorbers (protection)

Triglycerides are great for storing energy long-term
- Stable
- Insoluble → do not affect osmolarity
- Energy-dense (9cal/g compared to carbs 4 cal/g)

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B1.1.12

What is a phospholipid bilayer?
What role does it have in a cell?

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When you place phospholipids in watery solutions they arrange in a bilayer
- Tails pointing inwards (away from water)
- Heads pointing outward (towards the water)

Role:
- Helps compartmentalize the cells
- They determine the permeability, polar molecules like glucose can’t pass from the hydrophobic tails
Steroids are non-polar lipids so they can pass through
Ex: testosterone, 3 six-sided rings, and one five-sided ring

B1.2.1

What are amino acids?
What is the general structure of an amino acid?

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Amino acids are the building blocks of proteins
20 different types of amino acids

NH2 amine group - central carbon - COOH carboxyl group - hydrogen and R group

R group changes but the rest is identical for the rest

B1.2.2

What is a dipeptide and polypeptide?
How are they formed? What is the bond between amino acids?

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Dipeptide: 2 amino acids
Polypeptide: many amino acids
**Condensation reactions: **remove water to form a peptide bond between amino acids

B1.2.3

What are essential amino acids?
Dietary requirements for amino acids?

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20 different amino acids
Plants can produce all 20 amino acids.
Humans can only make** 9 **of them so we need to consume 11 of it in our diet

Many animal proteins do have all of the essential amino acids but if you have a vegan or plant-based diet we need to eat the variety of foods to make sure that we get all types of amino acids.

B1.2.5

How does pH and temperature affect protein structure?

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Changes in pH and temperature can lead to denaturation, a permanent change in protein structure and function.

A protein’s function is very specific to its shape

C1.1.1

What are enzymes, what is their role? What is metabolism?

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Catalysts that increase the rate of chemical reactions
Are not consumed, can be reused
Are protein-based.

Metabolism: all of the enzyme-catalysed reactions in a cell

Enzymes are substrate-specific (each substrate in each reaction needs its own enzyme)
Lots of different enzymes

C1.1.3

What are anabolic and catabolic reactions?

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Anabolic: small → bigger, forming bonds, requires energy (e.g., photosynthesis)
Catabolic: big → smaller, breaking bonds, releases energy (e.g., cell respiration, hydrolysis)

C1.1.5

What is the induced-fit model of enzyme action?

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The active site of an enzyme changes shape for substrate binding, facilitating the reaction.

After product is released, the active site returns to its original shape

What is activation energy?

**Activation energy:** energy required to get a reaction started Enzymes speed up reactions by lowering the activation energy

Effect of temperature on the rate of enzyme activity

1. Molecules move faster 2. Denaturation

What happens during denaturation of an enzyme?

A permanent change to the enzyme's 3D structure renders it unable to catalyze reactions.

Energy storage polysaccharides, in plants and in humans

In plants: **Starch: **Energy molecule in **plants** (comes in two forms) - **Amylose:** made out of **a-glucose**, **1-4** glycosidic bonds, spiral chain, **linear ** - **Amylopectin:** made out of **a-glucose**, **1-4 **and **1-6** glycosidic bonds, spiral with **branches ** In animals: **Glycogen: **Energy storage molecule in animals A-glucose with **1-4 **and **1-6** glycosidic bonds: highly **branched**

Starch

Starch: **Energy storage **molecule in **plants** (comes in two forms) - **Amylose:** made out of** a-glucose**, **1-4** glycosidic bonds, **spiral chain**, **linear ** - **Amylopectin:** made out of **a-glucose**, **1-4 **and **1-6** glycosidic bonds, spiral with **branches**

Glycogen

**Energy storage **molecule in animals **A-glucose **with **1-4** and **1-6 **glycosidic bonds: **highly branched**

# B1.1.9 What are triglycerides? How do we form them?

Triglyceride: **glycerol + 3 fatty acid chains** Connect the glycerol with fatty acids using a **condensation reaction** (**removing water molecules**) Entirely **hydrophobic**, non-polar, not soluble in water

# B1.1.9 What are phospholipids? What does amphipathic?

Phospholipid: **glycerol + 2 fatty acids + phosphate group** - The phosphate **head is polar**/hydrophilic (**glycerol and phosphate group**) - Fatty acid **tails are non-polar**/hydrophobic - This form a bilayer (**phospholipid bilayer**) - **Amphipathic:** they have both hydrophobic and hydrophilic parts

Types of polyunsaturated fatty acids?

Cis-unsaturated fatty acids - **Hydrogen atoms are on the same side** of the chain - Most **natural** fatty acids - Oils - Bend/kink in the chain Trans-unsaturated fatty acids - **Hydrogen atoms are on the opposite side** of the chain - **Straightens out** the chain - **Not naturally **occurring Solidify Health concerns

# B1.2.4 Explain the Infinite variety of possible peptide chains What is a proteome?

**DNA (has the code for the polypeptides) **→ RNA (carries the code to ribosome) → Polypeptide - 20 amino acids can be put together in different patterns, make them different lengths, etc. - Gives us infinite possibilities of different polypeptide that we can make **Proteome:** the set of proteins made by an organism **Important proteins/polypeptides :** Insulin, amylase, titin

What factors may cause denaturation of the enzymes? (Graphs)

**Heat ** - Breaks bonds or interactions between amino acids - The denaturation point varies for each protein First, as the temperature increases the protein becomes more and more active Then, the temperature reaches very high levels that it denature the protein so the protein cannot function anymore and the reaction rate drops to zero **pH** At its optimal pH rate, it functions well high reaction rate Low pH levels or high breaks the bonds and denatures Reaction rate will be highest in the middle (neutral pH)

Structure, form of an enzyme

Enzymes are: **- Globular protein - 3D - Soluble** **Shape is determined by** the amino acid sequence which is determined by the **DNA** that **folds into a specific shape** Have a **specifically-shaped active site**, which is where the substrate binds enzymes are specific to their substrates

Role of molecular motion and substrate-active site collisions in enzyme catalysis. What are the principles for collisions?

In order for chemical reactions to take place, **molecules must collide** The collisions have to cover two basic principles **1. Energy** - **Temperature increasing **(increases the movement of molecules) - **Concentration increasing** (make them collide more often) **2. Orientation** Must collide in the correct orientation

Active-site shape → substrate specificity How does denaturation affect this?

* Active site’s shape complement specific substrate(s). * Most enzymes fit one substrate; some accept a few closely related ones. * Denaturation (heat, pH, chemicals) irreversibly changes shape of the active site, so the substrate can’t bind

Effect of pH on the rate of enzyme activity

Effect of substrate concentration on the rate of enzyme activity

They will be colliding more frequently Then all active sites will be occupied (plateau)

Measurements in enzyme-catalysed reactions

Unit 6: General Biochemistry Flashcards

(41 cards)