Biochemistry Flashcards
What is the water cycle?
The continuous cycling of water between the earth and the atmosphere.
What is precipitation?
The movement of water from the atmosphere to the ground, including rain, fog, snow, hail, dew, and frost.
What process allows water to filter through the soil to the water table?
Infiltration.
What happens to water that does not infiltrate into the soil?
It runs off above the ground and forms streams that flow into lakes and the sea.
What is evaporation in the context of the water cycle?
The process by which water turns into water vapor from the ground and water bodies.
What do plants do in relation to water in the water cycle?
Plants transpire, losing water into the atmosphere as water vapor.
What occurs when water vapor condenses?
It forms clouds, which can lead to precipitation under the right conditions.
Fill in the blank: Water is continuously cycled between the earth and the _______.
atmosphere.
True or False: The water cycle includes only the processes of evaporation and precipitation.
False.
What is the chemical formula for oxygen found in the atmosphere?
O2
What is the role of oxygen in respiration?
Used by living organisms to break down food into CO2 and water
What do photosynthesizing organisms use from the atmosphere?
CO2
What is produced by photosynthesizing organisms during the formation of organic compounds?
Oxygen
Where is carbon dioxide found in addition to the atmosphere?
Dissolved in water
What happens to carbon compounds when consumers eat them?
Transferred to consumers
What process do bacteria perform when plants and animals die?
Break them down, releasing CO2 into the atmosphere
What can happen to organisms that do not decompose?
Compressed to form fossil fuels like coal and oil
How does oxygen interact with the earth’s rocks?
Can be both absorbed and released during surface weathering
What do fossil fuels release into the atmosphere during combustion?
CO2
Fill in the blank: Oxygen is found in the atmosphere as _______ and as part of other molecules.
O2
True or False: Aquatic organisms do not use oxygen dissolved in water.
False
What is the primary component of the atmosphere that is not usable by plants and animals?
Nitrogen gas
What processes convert nitrogen gas into nitrates?
Lightning and nitrogen-fixing bacteria
How do plants utilize nitrates?
To make proteins
What do animals produce when they eat plants?
Animal proteins
What happens to proteins when organisms die?
They are decomposed into ammonia by decomposing bacteria
What is contained in animal excretions that is converted to ammonia?
Urea
What type of bacteria convert ammonia into nitrites?
Nitrifying bacteria
What do nitrifying bacteria convert nitrites into?
Nitrates
What is the role of denitrifying bacteria in the nitrogen cycle?
Convert nitrates back into nitrogen gas
Fill in the blank: Nitrogen gas makes up most of the atmosphere but is not usable by plants and animals in this form. _______ and nitrogen-fixing bacteria convert nitrogen gas into nitrates.
Lightning
Elements making up carbohydrates
C, H and O
Ratio of oxygen to hydrogen in carbohydrates
1:2
Simplest unit of carbohydrates
Monosaccharide
What are two monosaccharides together called?
Disaccharides
Characteristic taste of disaccharides
Sweet
Solubility of disaccharides in water
Dissolve in water
Formation process of disaccharides
Condensation reactions
What are polysaccharides?
Many (three or more) monosaccharides linked together
Are polysaccharides soluble in water?
No, they are non-dissolvable in water
Do polysaccharides taste sweet?
No, they do not taste sweet
What is one use of carbohydrates for humans and animals?
Energy source
What is another use of carbohydrates for humans and animals?
Energy storage
What is one use of carbohydrates for plants?
Energy storage
What is another use of carbohydrates for plants?
Structural component
List at least ten different foods containing carbohydrates
Pasta, bread, rice, potato chips, wheat, potatoes, donuts, muffins, sugar, pastries
Carbohydrates are a major source of energy in the diet.
What is a general name for a molecule made up of lots of identical or similar subunits joined together?
Compound
This term refers to molecules formed from repeating units, often seen in polymers.
What is the chemical formula for a carbohydrate with 6 carbons, 6 oxygens and 12 hydrogens?
Glucose
Glucose is a simple sugar and an important energy source in living organisms.
If monosaccharides have 6 carbons each, how many carbons does lactose have?
12 carbons
Lactose is a disaccharide composed of two monosaccharides, each having 6 carbons.
If lactose has 12 carbons, how many hydrogens does it have?
24 hydrogens
The molecular structure of lactose results in this hydrogen count based on its composition.
What chemical reaction occurs when two saccharides are joined together?
Condensation reaction
This reaction involves the removal of a water molecule to form a new bond between saccharides.
What are the products of the condensation reaction between two saccharides?
Maltose, sucrose, lactose
These are examples of disaccharides formed from monosaccharide units.
What are lipids?
Organic substances that include fats and oils
Lipids are hydrophobic and play various roles in biological systems.
What elements make up lipids?
C, H, and O
These elements are found in varying ratios within different types of lipids.
What is the typical ratio of hydrogen to carbon in lipids?
Much more than 2:1
This indicates a high number of hydrogen atoms compared to carbon in lipid structures.
What are the properties of lipids?
Oily or greasy nonpolar molecules; either liquids or non-crystalline solids at room temperature
Their nonpolar nature makes them insoluble in water.
What is the basic structure of a lipid?
One glycerol molecule and three fatty acid molecules
This structure is typical of triglycerides, a common type of lipid.
What types of fatty acids influence lipid properties?
Saturated fats and unsaturated fats
Saturated fats are solid at room temperature, while unsaturated fats are liquid.
What is a characteristic of saturated fats?
They are hard at room temperature
This is due to the absence of double bonds in their fatty acid chains.
What is a characteristic of unsaturated fats?
They are liquid at room temperature
This is due to the presence of one or more double bonds in their fatty acid chains.
What role does cholesterol play in health?
Involved in heart disease; can cause plaque formation in arteries
High levels of cholesterol can lead to cardiovascular issues.
What elements make up proteins?
C, H, O, and N
Carbon, hydrogen, oxygen, and nitrogen are the primary elements found in proteins.
What is the simplest unit of proteins?
Amino acid
Amino acids are the building blocks of proteins.
How many different types of amino acids are there?
20
There are 20 standard amino acids that are used to build proteins.
What are two amino acids together called?
Dipeptide
Dipeptides are formed when two amino acids are linked by a peptide bond.
What is a three amino acids chain called?
Tripeptide
A tripeptide consists of three amino acids joined together.
What is the term for many amino acids joined together?
Polypeptide
Polypeptides are long chains of amino acids that form proteins.
What is a key characteristic of proteins?
Come in many different shapes and sizes
The diversity in protein structure allows for a wide range of functions.
What are some uses of proteins? (List at least three)
- Structural
- Catalysts (enzymes)
- Membrane pores
- Energy store
- Hormones
- Haemoglobin
- Antibodies
- DNA packaging
- Buffers
The various functions of proteins are directly related to their unique structures.
What elements make up nucleic acids?
C, O, H, N, and P
What is the simplest unit of nucleic acids?
nucleotide
What is the full name of DNA?
Deoxyribonucleic acid
Where is DNA found within the cell?
in the cell nucleus, in chromosomes or chromatin
What is the primary function of DNA?
carries the genetic information (inherited characteristics)
How many strands make up DNA?
2 strands
What is the full name of RNA?
ribonucleic acid
Where is RNA found within the cell?
in the nucleus and in the cytoplasm
What is a key role of RNA in the cell?
plays a role in protein synthesis
How many strands make up RNA?
1 strand
Fill in the blank: RNA is included in translating _______ into protein sequence.
DNA code
True or False: RNA can move between the nucleus and the cytoplasm.
True
What are vitamins?
Organic molecules essential for maintaining many chemical reactions in cells.
What are the two main types of vitamins?
Water-soluble and fat-soluble vitamins.
Which vitamins are water-soluble?
Vitamin B and C.
Which vitamins are fat-soluble?
Vitamins A, D, E, and K.
How often must water-soluble vitamins be renewed?
Daily from our diet.
How are fat-soluble vitamins absorbed?
They are absorbed with lipids in our diet.
What happens if we do not get sufficient vitamins in our diet?
We may get a vitamin deficiency disease.
What is another name for Vitamin C?
Ascorbic acid.
In which foods can Vitamin C be found?
Fresh fruits and vegetables, e.g., guavas and broccoli.
What role does Vitamin C play in the body?
Helps maintain the intercellular substances in bones, cartilage, and dentine.
What is a key function of Vitamin C related to connective tissues?
Helps to form collagen under the skin.
What is the deficiency disease associated with Vitamin C?
Scurvy.
What are food tests?
Simple tests to investigate which nutrients are found in different types of food
Food tests determine the presence of specific nutrients through chemical reactions.
What is a reagent in the context of food tests?
Chemicals added to test for different nutrients in food
Reagents are crucial for indicating the presence of specific food chemicals.
What is the purpose of Benedict’s solution in food testing?
To test for the presence of glucose
Benedict’s solution is initially blue and changes color based on glucose concentration.
What indicates a positive test result for glucose when using Benedict’s solution?
Color change from blue to green-yellow-orange-red
Orange-red indicates a high concentration of glucose.
What color indicates a high concentration of glucose in a Benedict’s test?
Orange-red
The color change is a qualitative measure of glucose concentration.
What indicates a negative test result for glucose?
No color change (stays blue)
A blue solution after heating indicates the absence of glucose.
What reagent is used to test for starch?
Iodine solution
Iodine solution changes color in the presence of starch.
What color change indicates the presence of starch when using iodine solution?
Blue-black
A blue-black color change is a clear indicator of starch.
What indicates a negative test result for starch?
No color change (stays light yellow-brown)
A light yellow-brown solution indicates the absence of starch.
How are lipids tested in food samples?
By grinding the sample with alcohol or ether and observing for a greasy spot
The greasy spot on filter paper indicates the presence of lipids.
What indicates a positive test result for lipids?
A translucent greasy spot on the filter paper
This result is observed after evaporating the alcohol or ether.
What indicates a negative test result for lipids?
No greasy spot on the dried filter paper
A lack of a greasy spot suggests the absence of lipids.
Fill in the blank: To test for glucose, a reagent called _______ is added to the sample.
Benedict’s solution
This solution is essential for detecting glucose in food samples.
Fill in the blank: A few drops of _______ solution are used as the reagent to test for starch.
iodine
Iodine is the standard reagent for starch testing.
True or False: A color change to blue-black indicates the presence of lipids.
False
Blue-black indicates starch, while lipids are indicated by a greasy spot.
What indicates the presence of lipids in a food sample?
An oily layer floating on the top of the sample
Lipids do not dissolve in water and are less dense than water.
What is the first step in testing for proteins?
Add dilute copper sulphate solution to the food sample
This is part of the Biuret test for proteins.
What solution is added after the copper sulphate in the Biuret test?
Sodium-hydroxide solution
Sodium hydroxide is an irritant and should be handled with care.
What color indicates a positive test for proteins in the Biuret test?
Purple/violet
A blue color indicates a negative test for proteins.
What does a blue color indicate in the Biuret test?
A negative test for proteins
This means that proteins are not present in the food sample.
Fill in the blank: Lipids do not dissolve in _______.
water
What are enzymes?
Proteins that act as biological catalysts
Enzymes speed up chemical reactions without being consumed in the process.
What are substrates?
Molecules upon which enzymes act
Enzymes convert substrates into products.
What are products in the context of enzyme activity?
Different molecules formed from substrates after enzymatic action
Products result from the chemical reactions catalyzed by enzymes.
Why are enzymes essential for metabolic processes?
They enable chemical reactions to occur at rates fast enough to sustain life
Almost all metabolic processes require enzymes.
What determines the three-dimensional shape of a protein?
The order of amino acids in the peptide chain
This specific structure is crucial for the protein’s function.
What is the ‘lock and key’ model?
A model explaining how enzymes and substrates interact
Enzymes are the ‘lock’ and substrates are the ‘key’.
What does the active site of an enzyme do?
It allows specific substrates to bond
The shape of the active site is crucial for substrate binding.
What happens to the enzyme after a reaction occurs?
The enzyme remains unchanged
It can be reused for subsequent reactions.
What are catabolic reactions?
Reactions that break down molecules
These reactions are facilitated by specific enzymes.
What are anabolic reactions?
Reactions that build up molecules
These reactions also involve specific enzymes.
How are enzymes usually named?
By combining the suffix -ase with the name of the substrate
Example: Lactase breaks down lactose.
Fill in the blank: Enzymes convert substrates into _______.
[products]
What is denaturation in the context of enzymes?
The process where the three-dimensional structure of a protein changes to the point that it can no longer function
What is the optimum temperature for enzyme activity in humans?
37°C
What happens to proteins at very high temperatures?
They denature, breaking down into their primary structure
How does denaturation affect the active site of an enzyme?
The shape of the active site is altered, preventing substrate binding
What effect do low temperatures have on enzyme activity?
They can slow down or even inactivate enzymes
How does pH affect enzyme activity?
Enzymes have an optimum pH and function effectively within a pH range
What happens to enzyme effectiveness when pH is outside its optimum range?
Effectiveness falls sharply and can lead to denaturation
Fill in the blank: Enzymes function best at _______ temperature.
37°C
True or False: Enzymes can function at any pH level without affecting their activity.
False
What is the primary structure of a protein?
A long chain of amino acids
