Food Flashcards
Why are nutrients essential?
As a source of energy
To make chemicals needed for metabolic reactions
As raw materials for the growth and repair of structures in an organism
What 6 common elements are found in food?
Oxygen, Hydrogen, Carbon, Nitrogen, Sulphur and Phosphorus
What four elements make up over 99% of the mass and atoms present in organisms?
Carbon, Hydrogen, Oxygen and Nitrogen
What are compounds made from carbon called?
Organic compounds
What are the five elements present in dissolved salts?
Sodium, Chlorine, Magnesium, Calcium, Potassium
Apart from what elements are minerals?
Apart from carbon, hydrogen and oxygen, the rest are minerals
What are the three trace elements?
Iron, Zinc, Copper
What are biomolecules?
Chemicals made inside a living thing
What do biomolecules contain?
Carbon and are also called biochemicals
What are the four major types of biomolecules?
Carbohydrates, Lipids, Vitamins and Proteins
What elements make up carbohydrates?
Carbon, hydrogen, Oxygen
What is the chemical formula of carbohydrates?
Cx(h2O)y where x = y
[always twice as much hydrogen as oxygen]
What are monosaccharides?
Consist of one single sugar unit and are the smallest units of carbohydrates
They are sweet to taste and soluble in water
What is a sugar unit?
Ring of carbon atoms
Give two examples of monosaccharides?
Glucose and Fructose
What is glucose and where is it found
An example of a monosaccharide, Organisms get their energy, found in fruit sweets, chocolate and in plants it’s made during photosynthesis
What is fructose?
Sweeter than glucose + found in fruit
What is a disaccharide?
Two monosaccharides joined together
Give examples of disaccharides
Sucrose, Maltose, Lactose
What is sucrose?
Glucose and fructose [table sugar]
What is maltose?
glucose + glucose molecules [barley]
What is lactose?
Glucose and galactose [milk]
What are polysaccharides?
Many monosaccharides linked together
Insoluble or only slightly soluble
Give examples of polysaccharides?
Starch, cellulose, Glycogen
What is starch?
Polysaccharide Carbohydrate stored by plants. Long chains of glucose molecules and is easily digested bc glucose molecules are arranged in line
Give sources of starch
Rice, potatoes, flour, bread and pasta
What is cellulose?
A structural carbohydrate in plants. Consists of long chains of glucose molecule cross bonding between chains.
Due to the bonding of cellulose, what features does it have
More difficult to break down [digest] than starch which is why it is used as a fibre in diet. Fibre stimulates peristalsis
Very strong, used in cell walls of plants
Sources of cellulose
Paper and cotton
What is glycogen?
It’s a carbohydrate stored by animals. Made of many glucose molecules more branched. Mostly stored in liver and muscles
What are sources of carbohydrates?
Bread, potatoes, rice, sugars, fruits
What is the structural role of carbohydrates?
Cellulose used to from plant cell walls
What is the metabolic role of carbohydrates
Broken down to release energy in respiration [also glucose in photosynthesis]
What are the elements present in lipids?
Carbon, hydrogen and oxygen
What are fats?
Lipids that are solid at room temperature
What are oils?
Lipids that are liquid at room temperature
What are the smallest lipids made up of?
One molecule of glycerol linked to three fatty acid molecules
What are phospholipids
They are fat-like substances where one of the fatty acids is replaced by a phosphate group
Give sources of lipids
Butter, oils, margarine, cream
What is the structural role of lipids?
Stores energy
Insulation - stored lipids insulate [fat under skin] and protect organs [fat around heart and kidneys]
Lipids combine with phosphorus to form phospholipids = important in structure of cell membrane
What is the metabolic role of lipids?
Broken down to release energy in respiration
What are the elements present in protein?
Carbon, hydrogen, oxygen and nitrogen [sometimes sulfur and phosphorus]
What are proteins compose of?
Amino acids
What is a bond between amino acids called?
Peptide bond
What is a peptide?
Small number of amino acids
What is a polypeptide?
Has more than 20 amino acids
What is a protein?
It’s a long polypeptide [200 amino acids]
What does protein function depend on?
Amino acid sequence
Way in which proteins are folded to take up 3D shapes
What are fibrous proteins?
Show little or no folding, strong + tough eg, keratin in hair and nails
What are globular proteins?
Show lots of folding, from round shapes eg, enzymes
Sources of protein?
Red meat, fish, eggs
Are amino acids stored in the body?
No, surplus amino acids we taken to the live and converted into urea, which is a toxic wast product. This is known as deamination. Urea is carried by the blood to the kidneys and here it becomes part of urine and is excreted
What reagent is used for testing for glucose [reducing sugar]
Benedicts solution
What are the negative and positive results of testing for a reducing sugar?
Negative - blue
Positive - red
What is the reagent used to test for starch?
Iodine
What are the positive and negative results of testing for starch?
Negative - red/yellow
Positive - blue/black
What is the reagent used for fat?
Brown paper
What are the positive and negative results of fat?
Negative - no stain
Positive - permanent translucent stain
What regent is used to test for protein?
Sodium hydroxide + copper sulfate
What are the positive and negative results of testing for protein?
Negative - blue
Positive - purple/violet
What are vitamins?
They are complex carbon-based substances that the body cannot make
Give an example of a fat-soluble and its function
Vitamin D - strong bones + teeth
What occurs when there is a efficient of vitamin d
Rickets
Osteomalacia in adults
Weak, deformed bones
Sources of vitamin d
Dairy, sunshine
Give an example of a water soluble vitamin and give its function
Vitamin c - makes connective tissue + keeps healthy
What occurs when there is a deficiency of vitamin c?
Scurvy
Sources of vitamin c?
Citrus fruits
What is the structural role of proteins?
Keratin found in hair
What is the metabolic role or proteins?
Enzymes, some hormones and antibodies
What is the metabolic role of vitamin c?
Forms connective tissue + bones and teeth
What is the metabolic role of vitamin d?
Helps absorb calcium for bones and teeth
What are anabolic reactions and give an example
They convert smaller molecules into larger ones. They require energy and enzymes eg, photosynthesis, plants get energy from sun and use it to convert co2 and water into glucose.
What are catabolic reactions and give an example
A complex molecule is broken down into simpler ones, require energy and enzymes eg, respiration. A complex molecule such as glucose is broken down to simpler molecules which releases energy
Name two minerals that are needed for plants, where is it found and why do they need it
Calcium - salts absorbed from soil and it helps bind cell walls together
Magnesium - salts absorbers from soil and it forms part of structure of chlorophyll
Name two minerals that are needed in animals?
Calcium - milk, cheese - forms strong bones and teeth
Iron - meat, green vegetables - part of structure of haemoglobin
Why is water essential to life?
The liquid in which all metabolic reactions take place
Basis for transport systems in organisms
Environment in which many organisms live
What are the importances of water?
Component of cytoplasm and body fluids Good solvent Participates in chemical reactions Movement through membranes Good absorber of heat
Water is a component of cytoplasm and body fluids
Water is mainly found in cytoplasm which is the liquid that surrounds the nucleus in a cell. In humans 1/3 of the body’s water is found outside cells. Some of this is in the form of tissue fluid, which surrounds all body cells and the rest forms plasma
How is water a good solvent?
It’s able to dissolve a wide range of molecules which allows chemical reactions to take place in water
Also allows many molecules to be dissolved in water for transport
How does water participate in chemical reactions?
Biochemical reactions - condensation reactions, hydrolysis reactions, photosynthesis and respiration
What are condensation reactions?
Smaller molecules join to form a larger molecules with the loss of a water molecule eg, formation of maltose from two glucose molecules
What are hydrolysis reactions?
Where a molecule gains water and is broken down to form smaller molecules eg, amino acids
What is photosynthesis in relation to water chemical reactions
Where water is broken down to supply hydrogen and oxygens
What is respiration in relation to chemical relations in water
Respiration - water is formed as an end product
How does water allow the movement through membranes?
Water can easily pass in or out through biological membranes. When cells absorb large amounts of water they become swollen. If cells loose water they shrivel up and lose their shape. The loss of shape = serious results for the function of the cell.
Give examples on how the loss of a shape of a cell can have serious impacts on both an animal and plant
Animal - red blood cells lose shape, they absorb and carry less oxygen
Plants - overall plant may lose shape [wilting]
How is water a good absorber of heat?
It is slow to heat up and slow to cool down. This means that the oceans and larger bodies of water have relatively stable temperatures
The high water content of organisms helps to keep temperature stable. This allows biological reactions to take place over a narrow temperature range [the speed at which biological reactions take place is very dependent on temperature]
What is the most common value of y in the carbohydrates used for energy by human cells?
6
Which carbohydrate is always found in DNA?
Deoxyribose
Difference between amino acids and protein
Amino acids - unit of protein
Proteins - made up of amino acids
Difference between enzymes and hormones
Enzymes - Protein speeds biological reactions
Hormones - a chemical messenger
Name a polysaccharide that can be formed from glucose
Starch
How do a in acids differ from a monosaccharide in terms of chemical composition
Contains N
What do carbohydrates and fats have in common in terms of chemical composition
C H O
How may one fat differ from another, in terms of chemical composition
Different fatty acids
What is meant by a trace element?
Small amount is needed
Vitamins are divided into two groups
Fat soluble
Water soluble
How many common amino acids are found in protein?
At least 20
What is the most common value of y in the carbohydrates used for energy by human cells?
6
Which carbohydrate is always found in DNA?
Deoxyribose
Difference between amino acids and protein
Amino acids - unit of protein
Proteins - made up of amino acids
Difference between enzymes and hormones
Enzymes - Protein speeds biological reactions
Hormones - a chemical messenger
Name a polysaccharide that can be formed from glucose
Starch
How do a in acids differ from a monosaccharide in terms of chemical composition
Contains N
What do carbohydrates and fats have in common in terms of chemical composition
C H O
How may one fat differ from another, in terms of chemical composition
Different fatty acids
What is meant by a trace element?
Small amount is needed
Vitamins are divided into two groups
Fat soluble
Water soluble
How many common amino acids are found in protein?
At least 200
Name the substance used as a control in Benedicts test
Water
How did you add a very small volume of a solution when carrying out certain routine procedures
Pipette
Name a catabolic process that produces the simpler units of carbohydrates
Digestion
How does a phospholipid differ from a fat?
Phospholipid contains glycerol and fatty acids where one of the fatty acids is replaced by a phosphate group
Fat : glycerol and three fatty acids
Distinguish between starch and glucose
Starch - polysaccharide
Glucose - monosaccharide
Distinguish between amino acids and proteins
Amino acids - unit of protein
Proteins - chains of amino acids
Distinguish between cellulose and keratin
Cellulose - carbohydrate [found in plant cell wall]
Keratin - protein [found in human skin/hair/nails]
Distinguish between enzymes and hormones
Enzymes - catalyst
Hormones - messenger
Distinguish between biuret test and Benedicts test
Buiret - test for protein [blue to violet]
Benedicts - test for reducing sugar [blue to red]
Distinguish between fats and oils
Fats - solid lipids at room temperature
Oils - liquid lipids at room temperature
- name a monosaccharide
- give the formula
- name a polysaccharide that can be formed from the monosaccharide named above
- glucose
- c6h12o6
- starch
What do carbohydrates and fats have in common in terms of chemical composition
Both have C, O and H
How may one fat differ from another in terms of chemical composition?
Different fatty acids
What is a triglyceride?
Glycerol and three fatty acids
Example of a catholic reaction IN A CELL
Respiration
Example of an anabolic IN A CELL
Photosynthesis
A person who has suffered from constipation may be advised to inc the amount of cereal in their diet, why?
Contains fibre which stimulates peristalsis [also absorbs water] which allows for faster digestive transit
In carbohydrates, which two elements are in the ratio 2:1?
Hydrogen and oxygen
Safety precaution for reducing sugar experiment
Heat but do not boil
Is energy release a feature of anabolic or catabolic reactions?
Catabolic
For which purpose did you use biuret solution?
To test for protein
For what purpose did you use brown paper?
To test for fats
How was the glucose soltuion heated?
Using a water bath
