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Biology > Module 2: Foundations In Biology > Flashcards

Module 2: Foundations In Biology Flashcards

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1
Q

What is the function and structure of the nucleus?

A

The nucleus’ function is to contain the DNA, and by extension to control the growth and reproduction of the cell. The DNA is contained within a double membrane called the nuclear envelope. The nuclear envelope has pores called nuclear pores which allow molecules(such as mRNA for protein synthesis) to enter and leave the nucleus

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2
Q

What is the structure and function of the nucleolus?

A

The nucleolus’ main function is to assemble ribosomes. It is made up of pre-RNA and proteins. It makes ribosomes by using the rna that it’s made out of to make ribosomal rna

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3
Q

What is the function and structure of the cytosol?

A

The cytosol’s main function is to transport signals across the cell between the nucleus and other organelles. It is mainly made out of water

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4
Q

What is the function and structure of the ribosomes?

A

Ribosomes are where protein synthesis takes place. They make proteins by reading the mRNA that has been transported from the nucleus and bonding amino acids together. They are made out of ribosomal RNA and proteins

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5
Q

What is the function and structure of the cytoskeleton?

A

The cytoskeleton forms the shape of the cell and organises the movement of the organelles. It is made up of micro tubes, microfilaments(made of actin) and intermediate filaments. Microtubes form the shape of the cell and are what spindle fibres used for mitosis are made of, microfilaments are responsible for cell movement and the cell contraction during mitosis and intermediate filaments give strength to the cells and maintain their integrity

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6
Q

What is the function and structure of the mitochondria?

A

Mitochondria are the site of aerobic respiration, the process that makes ATP energy for the body. Mitochondria have 2 membranes. The inner membrane is highly folded, forms structures called cristae and contains enzymes used in the aerobic respiration. The fluid interior is called the matrix. In the centre of the mitochondria is smaller mitochondrial dna which helps the mitochondria produce their own enzymes and replicate

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7
Q

What is the function and structure of the vesicles?

A

Vesicles transport materials around the cell. They are made up of a single membrane with fluid inside

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8
Q

What is the function and structure of lysosomes?

A

Lysosomes are specialised forms of vesicle. Their function is to break down waste material in the cell, for example, pathogens that have been engulfed by phagocyte cells. They also play a role in apoptosis, which is the programmed death of the cell

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9
Q

What is the function and structure of centrioles?

A

Centrioles are components of the cytoskeleton made up of microtubes. 2 centrioles form the centrosome, which makes spindle fibres used for mitosis. They are also believed to control the positioning of flagella and cilia in cells that have them.

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10
Q

What are the functions and structures of flagella and cilia?

A

Flagella and cilia are extensions that protrude of the cells that have them. Flagella are used to control cell motility and sometimes they are used as sensory organelles that can sense chemical changes the the environment. Cilia come in two forms: mobile and stationary. Stationary cilia are used as sensory organelles, especially in body parts such as the nose. Mobile cilia move rhythmically to create a current that moves fluids and substances across the cell(such as mucus in the trachea)

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11
Q

What is the function and structure of the endoplasmic reticulum?

A

The ER is a network of membranes that is made out of enclosed sacs called cisternas and is connected to the outer nuclear membrane. Smooth endoplasmic reticulum is responsible for the storage and synthesis of lipids and carbohydrates. Rough endoplasmic reticulum has ribosomes attached to it and is responsible for the transport and synthesis of proteins

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12
Q

What is the function and structure of the Golgi apparatus?

A

The structure of the Golgi apparatus is similar to the smooth endoplasmic reticulum, in the sense that it is compact, is formed of cisternas and doesn’t have ribosomes. It is responsible for modifying proteins and storing them in vesicles/lysosomes.

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13
Q

What is the function and structure of the cell wall?

A

The cell wall is only found in plants. It is made up of cellulose, which is a permeable complex carbohydrate. Because it is permeable, it allows substances to pass through it. It’s main function is to support the plant and give it its shape. It is rigid for support and it also acts as a defence mechanism against invading pathogens.

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14
Q

What is the function and structure of the chloroplasts?

A

Chloroplasts are responsible for photosynthesis in the leaves. Similar to the mitochondria, they have 2 membranes. The membranes enclose a fluid called stroma. They also have a network of membranes which form flattened sacs called thylakoids. Multiple thylakoids joined together are called a granum. The grana are where the chlorophyll used for photosynthesis is kept

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15
Q

What are the main differences between eukaryotic and prokaryotic cells?

A

Eukaryotic cells have linear chromosome DNA enclosed in a nucleus, whereas prokaryotic cells have free to move DNA that can be either in a circular plasmid form or as loose strands. Prokaryotic cells also don’t have any membraned organelles and are much smaller than eukaryotic cells. The cell wall of eukaryotic cells is made of cellulose, whereas the cell wall of prokaryotic cells is made of murein

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16
Q

What is resolution?

A

The ability to distinguish between 2 points

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17
Q

What is the function and structure of a cell capsule?

A

The cell capsule is a sticky layer on the outside of a prokaryotic cell. Is is made of sugar polymers and helps the organisms cling to each other as well as stick to various surfaces in the environment. The capsule also helps prevent the cell from drying out

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18
Q

What is the function and structure of the phospholipid bilayer?

A

It is made up of phospholipids. These are made up of hydrophilic phosphate heads and hydrophobic tails. It’s function is to form a membrane that can interact with water

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19
Q

What are intrinsic and extrinsic proteins?

A

Intrinsic proteins are proteins that are embedded between both layers of the phospholipid bilayer and are responsible for transport through the membrane. Extrinsic/peripheral proteins are proteins that are only embedded within one layer

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20
Q

What are channel proteins?

A

Intrinsic proteins whose function is to provide a pathway for passive transport(ie osmosis and diffusion)

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21
Q

What are carrier proteins?

A

Intrinsic proteins whose function is to carry substances through the membrane during active transport

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22
Q

What is the function and structure of glycoproteins?

A

They are proteins with carbohydrate chains attached to them. They play a role as receptors to detect chemical signals

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23
Q

What is the structure and function of glycolipids?

A

Lipids with attached carbohydrate chains. They act as the antigens so the cell can be recognised

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24
Q

What is the function and structure of cholesterol?

A

It is a lipid with a hydrophobic end and a hydrophilic end. It regulates the fluidity of membranes. It is an alcohol made out of 4 carbon rings with a hydroxyl group on the end

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25
Q

What is diffusion?

A

Diffusion is the net random movement of particles from an area of higher concentration to an area of lower concentration down a concentration gradient until equilibrium is reached

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26
Q

What is facilitated diffusion?

A

Diffusion but the molecules travel through the intrinsic proteins

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27
Q

What is active transport?

A

When molecules travel from an area of lower concentration to an area of higher concentration. It requires ATP energy and a carrier protein to move the molecules from one side of the membrane to the other

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28
Q

What is bulk transport?

A

Active transport for larger molecules/particles/bacteria. Endocytosis is bulk transport into the cell whereas exocytosis is bulk transport out of the cell

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29
Q

What is the process for endocytosis?

A
  1. Particles arrive at the cell membrane
  2. The cell membrane will invaginate(bend inwards) until the ends fuse with each other, forming a vesicle
  3. The vesicle that surrounds the particle will disconnect from the membrane and be carried across the cytoplasm to wherever it’s needed
30
Q

What is osmosis?

A

The movement of water particles down a concentration gradient from an area of higher water potential to an area of lower water potential across a partially permeable membrane

31
Q

What happens when an animal cell is in a solution with higher water potential than it?

A

The solution is hypotonic. Due to the cell having lower water potential, water will travel by osmosis from the solution into the cell. This will cause the cell to swell and burst, which is called lysis

32
Q

What happens when an animal cell is placed in a solution with lower water potential than it?

A

The solution is hypertonic. Due to the cell having a higher water potential, water will leave the cell by osmosis into the solution. The cell will become shrivelled, or crenated.

33
Q

What happens when a plant cell is in a solution with higher water potential than it?

A

The solution is hypotonic. Due to the cell having lower water potential, water will enter the cell my osmosis, this will cause the cell to swell but it won’t burst due to the cell wall. The cell is turgid(which is healthy as it helps maintain pressure to remain rigid)

34
Q

What happens when a plant cell is in a solution with lower water potential than it?

A

The solution is hypertonic. Due to the cell having higher water potential, water will exit the cell by osmosis. The cell keeps it’s shape due to the cell wall but its membrane shrivels up. The cell is plasmolysed and will eventually die

35
Q

What happens when a cell(animal or plant) is in a solution with the same water potential?

A

The solution is isotonic. Due to the cell and solution having the same water potential, no water travels by osmosis.

36
Q

What properties of water make it necessary for life?

A

The fact that’s it has hydrogen bonds means that ice is less dense than water and since water also has a great heat capacity it can act as an insulating layer which keeps aquatic life warm and alive. It’s cohesive and adhesive properties allow it to bead up on our skin, which is why sweat is so effective at drawing heat away. Along with the fact that water is polar, it’s cohesive and adhesive properties also mean that water is a great medium, because it can dissolve substances and travel against gravity in what’s called capillary action

37
Q

What is the structure of cellulose?

A

Long chains of beta glucose molecules with every alternate one being upside down. Each chain bonds together with hydrogen bonds to make microfibrils which bond together to make macrofibrils which bond together again to make fibre

38
Q

What are the two types of starch and what are their structures?

A

Both types are long chains of alpha glucose molecules. In amylose the glucose molecules bond between carbon 1 and carbon 4. In amylopectin there are also 1-4 carbon bonds but also branches at carbon 6 and carbon 1

39
Q

What is the structure of triglycerides?

A

Triglycerides are non-polar lipids made out of one glycerol molecule and 3 fatty acids. Glycerol is C3H8O3. Fatty acids can range in length, having a carbon chain ranging from 14-22 carbons. Saturated fatty acids have only single bonds and are solid at room temperature, a double bond makes the fatty acid unsaturated and are liquid at room temperature. The fatty acids are bonded to the glycerol by ester bonds and the formation of triglycerides is called esterification(it is a condensation reaction so produces water)

40
Q

What is the structure of ATP?

A

ATP(or Adenosine triphosphate) is made out of adenine(that acts as a nitrogenous base), ribose(which acts as a penthouse sugar) and 3 phosphate groups.

41
Q

How does ATP release energy?

A

ATP reacts with water to produce ADP and a lone phosphate ion. Although that reaction is endothermic which takes in energy, the lone phosphate ion will undergo an exothermic reaction with something else which releases a lot of energy. The two reactions happen at the same time so are considered to be coupled reactions

42
Q

What is phosphorylation and why is it useful?

A

The breaking down of fats and carbohydrates. The energy released is used to bind ADP to phosphate ions to make ATP which creates a cycle of ATP and ADP. This is useful as ATP cannot be stored long term but ADP can so with phosphorylation we can have a constant source of ATP and therefore energy

43
Q

What is the food test for starch?

A

Add iodine and if starch is present, it will turn blue-black as it forms a coloured poly-iodide complex

44
Q

What is the food test for reducing sugar(glucose)?

A

Add Benedict’s solution and heat in a 100° water bath. If glucose is present, it will turn brick-red or green, yellow or orange if the sugar is of a low concentration. This is because the sugar reduces the copper(II) ions in the Benedict’s solution to copper(I) oxide.

45
Q

What is the food test for non reducing sugar (for example sucrose)?

A

Add dilute hydrochloric acid, shake, place in a 100° water bath for 5 mins, add sodium hydroxide to neutralise, add Benedict’s and heat in a 100° water bath. If sucrose is present, it will turn brick-red as the acid hydrolyses the sucrose into glucose and fructose which give a positive Benedict’s test

46
Q

What is the food test for protein?

A

Add biuret’s solution. If protein is present it will turn lilac/mauve. This is because the nitrogen atoms in the peptide bonds of the protein form a lilac complex with the copper(II) ions in the biuret

47
Q

What is the food test for lipids?

A

Add ethanol, shake and add water. If lipids are present, a white precipitate will form as the alcohol mixes with the water, leaving the lipid to form an emulsion of microscopic droplets that suspend at the surface

48
Q

What’s the difference between reducing sugars and non reducing sugars?

A

Reducing sugars have free carbonyl groups so give a positive Benedict’s test. Examples include all monosaccharides and some disaccharides. Non-reducing sugars have no free carbonyl groups so don’t give a positive Benedict’s test. Examples include sucrose and all polysaccharides

49
Q

What is the chemical structure of proteins?

A

Long chains of amino acids(organic molecules with amine groups and carboxylic acid groups) that bond together with peptide bonds. Alongside the peptide bonds between each amino acid, there are R group interactions to give them their complex shape

50
Q

What is primary structure of proteins?

A

The sequence of the main chain of amino acids

51
Q

What is secondary protein structure?

A

The shape of the chain of amino acids. Alpha helixes are twisted and have hydrogen bonds between the C=O and the N-H groups, whereas beta folds are pleated sheets with hydrogen bonds in parallel chains

52
Q

What is tertiary structure of proteins?

A

The 3D shapes of the polypeptide chains. They are held together by chemical bonds(hydrogen, ionic and disulphide) and hydrophobic reactions between the R groups. Fibrous proteins are long coiled chains whereas globular proteins are spherical

53
Q

What is quaternary structure of proteins?

A

Some proteins are made out of multiple polypeptide chains bonded together by the same bonds as in tertiary structure

54
Q

What is the structure and function of insulin?

A

Insulin is a spherical tertiary protein that has it’s hydrophobic R groups on the outside. It is a hormone that regulates blood glucose levels

55
Q

What are conjugated proteins?

A

Proteins that have other non-protein components. For example, haemoglobin and catalase both have haem groups in them

56
Q

What is the structure and function of catalase?

A

It is a quaternary protein with 4 haem groups. It is an enzyme that has a specific shape to break down hydrogen peroxide

57
Q

What are the functions and properties and keratin?

A

Keratin is a protein that forms the hair, nails and outer layer of skin. It is strong, insoluble, fibrous and has ranged flexibility but is generally inflexible

58
Q

What are the functions and properties of elastin?

A

Elastin is a protein that forms elastic fibres, which are important tissues used all around the body. They are strong, flexible and elastic

59
Q

What are the functions and properties of collagen?

A

Collagen is a connective tissue found in the skin, tendons, ligaments and nervous system. It is strong and flexible

60
Q

What is the structure of DNA?

A

DNA is made out of nucleotides. Each nucleotide consists of a phosphate group, a deoxyribose sugar and a nitrogenous base, being one of adenine, thymine, guanine and cytosine. The phosphate and pentose sugar bond together between molecules with phosphodiester bonds to create a sugar-phosphate backbone which creates a strand and 2 strands join by the bases(A with T, C with G) to create a double helix DNA molecule

61
Q

What is the difference in structure between RNA and DNA?

A

RNA has ribose instead of deoxyribose as a sugar, only has one strand and has uracil as a base instead of thymine

62
Q

What are the steps of DNA replication?

A
  1. The enzyme helicase breaks the hydrogen bonds between the DNA strands and uncoils them.
  2. As the helicase is finishing uncoiling the DNA strands, free nucleotides start to be attracted to their complementary bases
  3. DNA polymerase combines the nucleotides to the original strands and corrects any errors.
  4. All the nucleotides join together to create 2 identical DNA molecules, each containing one strand from the original. Because of this, it is called semi-conservative replication
63
Q

What is the process of protein synthesis?

A

Transcription:
1. The section of the DNA with the protein genes uncoils through the helicase enzyme
2. Free RNA nucleotides will bond to the base of the DNA nucleotides, with uracil bonding to adenine as there is no thymine base in RNA
3. RNA polymerase forms phosphodiester bonds between the RNA nucleotides to form messenger RNA, or mRNA
4. The mRNA molecule then leaves the nucleus and travels to the ribosome
Translation:
5. The mRNA binds to the small subunit of the ribosome by its start codon
6. A transfer RNA molecule with the complementary anticodon binds to it
7. The ribosome reads the mRNA and translates it by attaching the corresponding amino acid to each other, forming a long chain
8. When the final mRNA codon is read, the chain is finished so it breaks off of the ribosome, folds into its secondary and tertiary structures and travels to the Golgi apparatus to be modified further

64
Q

Which monosaccharides are the 3 main disaccharides made out of?

A

Glucose + glucose = maltose
Glucose + fructose = sucrose
Glucose + galactose = lactose

65
Q

What is the nature of genetic code?

A

Triplet: DNA is read in groups of 3
Non-overlapping: when it reads, it does not overlap so no nucleotide is read twice
Degenerate: there are more combinations of code than amino acids so multiple combinations can code for the same amino acid
Universal: the same combinations code for the same amino acid regardless of organism

66
Q

How can Thin Layer Chromatography be used to find what amino acids are in an amino acid solution?

A
  1. A pencil line is drawn about 2cm above the bottom of a TCL plate(usually metal or glass)
  2. 4 equally spaced points are marked on the line
  3. The amino acid solution is spotted on the first dot and the other dots are spotted with known amino acids
  4. The plate is placed 1cm deep into a solvent(usually silica gel)
  5. The solvent will rise up the plate and carry the acids with it
  6. Once the solvent is 2cm away from the top, the plate is taken out, a pencil line is drawn along the top of the solvent and the plate is dried
  7. The plate is sprayed in a fume cupboard with ninhydrin spray. This reacts with the amino acids and forms a purple/brown colour
  8. The retention factors of the solution and the known amino acids are compared to find what amino acids are in the solution.
67
Q

What are the structure and functions of enzymes?

A

Enzymes are globular proteins with a highly specific shape and active site due to the r groups of the amino acids. Their function is to act as biological catalysts. They speed up both catabolic and anabolic reactions by lowering the activation energy.

68
Q

What is the Lock and Key model and the Induced Fit model?

A

Every enzyme has a specific shape that is complementary to the shape of specific substrate. Once the enzyme and substrate bind to form an enzyme-substrate complex, the enzyme undergoes more conformational changes to fit better

69
Q

What are some examples of enzymes and what do they catalyse?

A

Catalase-breaks down hydrogen peroxide into oxygen and water. It is intracellular
Carbohydrases-these are extracellular, break down carbohydrates and include:
Amylase-breaks down starch into maltose. It is found in the saliva and small intestine
Maltase-breaks down maltose into glucose. It is found in the small intestines
Proteases-these are extracellular, break down proteins and include trypsin and pepsin

70
Q

What is competitive inhibition and what are some examples?

A

Competitive inhibition is when a molecule/chemical/substance that has the same shape as a substrate binds with the active site of a complementary enzyme. This renders the enzyme unable to form enzyme-substrate complexes, reducing reaction rate. An example of a competitive inhibitor is statins, a drug used to inhibit the enzymes that increase cholesterol production rates. This is reversible as the statins can fall out of the enzyme. An irreversible inhibitor is aspirin, which inhibits the enzymes that produce pain-causing chemicals

71
Q

What is non-competitive inhibition and what are some examples?

A

When a substance binds to the non-specific part of an enzyme(the allosteric sites) it causes a conformational change and the enzyme can no longer with with its complementary substrate. This is usually irreversible. An example of this is organophosphate, a chemical that inhibits the enzyme acetyl cholinesterase.

72
Q

What is end-product inhibition?

A

A type of non competitive inhibition in which the product of a chain reaction blocks the first enzyme in the chain to prevent more products from being made. An example of this is ATP blocking PFK(the first enzyme in the respiration process) when there is too much ATP in the cells, only being released once the ATP levels drop

Biology (5 decks)

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