Module 2: Foundtions In Biology Flashcards
(119 cards)
1
Q
What are the functions of Golgi vesicles?
A
- Transports substances in and out of the cell via the plasma membrane.
2
Q
What are the functions of the cytoskeleton?
A
- Provides mechanical strength to cells, helps with transport within cells, and allows cell movement.
- Many organelles are bound to the cytoskeleton.
3
Q
What are the functions of the Golgi apparatus?
A
- Proteins and lipids are modified here.
- Makes lysosomes
4
Q
What are the functions of the mitochondria?
A
Site of aerobic respiration and ATP production.
5
Q
What are the two main differences between eukaryotic cells and prokaryotic cells?
A
- Eukaryotic cells have ethier DNA in the nucleus
- Eukaryotic cells are larger than prokaryotic cells
6
Q
What is the function of smooth endoplasmic reticulum(SER)?
A
Syntheisises and processes lipids
7
Q
What is the function of a ribosome?
A
- They are the site of protein synthesis
8
Q
Which stem cells can differrentiate into any types of cells?
A
Totipotent Cells
9
Q
When does DNA replication occur?
A
During interphase or S-phase
10
Q
What is the longests stage of the cell cycle?
A
Interphase
11
Q
What is the function of the rough endoplasmic reticulum (RER)?
A
Processes proteins
12
Q
What is the function of the plasma (cell surface) membrane and what is it made up of?
A
Function
-It regulates what goes inside and outside a cell
-It also has receptor molecules on the surface of cell membranes that allows it respond to chemicals like hormones.
Make up
-It is made up of lipids(phospholipid bilayer) and proteins(protein channels)
13
Q
What is the function of the chloroplasts?
A
The site of photosynthesis.
14
Q
What is the function of the centriole?
A
- It contracts the spindle allowing the separation of chromosones during mitosis
15
Q
What is the function of lysosomes?
A
- They contain digestive enzymes that help to digest invading cells or break down worn out components of cells.
- A type of Golgi vesicle that releases lysozymes.
16
Q
What is the function of cholesterol?
A
Cholesterol provides strength and reduces fluidity
17
Q
What is the function of a Nucleus?
A
- Nucleolus(found in the nucleus) is the site of rRNA production and makes ribosomes
- DNA replication and transcription occur in the nucleus.
18
Q
What is the function of a cell wall?
A
- It provides structural support.
- It prevents cells from bursting when water enters the cell by osmosis
19
Q
What is the function and description of Cillia?
A
Description
-Small hair like structures found on the membrane of some animal cells.
- In crosssection, they have an outer membrane and a ring of 9 pairs of proteins microtubules and two pairs in the middle.
Functions
- Microtubules allow the cillia to move so they can move substances along the cell surface
20
Q
What are the functions of water?
A
– Water is a reactant in metabolic reactions e.g hydrolysis reactions
– Water is a solvent so this means that substances can dissolve in it. Most biological reactions take place in the cytoplasm of cells.
– water transports sustances. Water is a liquid and a solvent, this makes it easy to transport substances like glucose and oxygen.
– water has a high specific heat capacity so it can buffer chnages in temperature. Water also has a high latent heat of vaporisation.
– Water is a habitat (to animals in the sea). water becomes less dense when it freezes meaning when its cold, only the top layer freezes so animals inhabiting in the water can still survive and reproduce.
21
Q
What the function of DNA polymerase?
A
makes the phosphodiester bonds between adjacent nucleotides
22
Q
What type of cell makes up the cambium tissue?
A
Meristem
23
Q
What is the name of the bond that hold water molecules together?
A
Hydrogen bond
24
Q
Why is water a good solvent?
A
– Water molecules are polar
– tis makes it able to attract a solute molecule
25
Calcium ions?
-- Involved in the transmission of nerve impulses and the release of insulin from the pancreas
-- Acts as a cofactor formany enzymes.
-- important in bone formation
26
Sodium ion?
-- Important for generating nerve impulses
-- Muscle contraction
-- importatnt for regulating fluid balance in the body,
27
Potassium ions?
-- Important for generating nerve impulses.
-- Muscle contraction
-- Regulating fluid balance in the body
-- Activates essential enzymes needed for photosynthesis.
28
Hydrogen ions?
-- Affects pH of substances
-- Important forphotosyntheis reactions.
29
Ammonium ions?
-- Absorbed by plants as it's an important source of nitrogen
30
Nittrate ions?
-- Absorbed from the soil by plants as it an important surce of nitrogen.
31
Hydrogencarbonate ions?
-- Acts as a buffer which helps to maintain pH of the blood.
32
Chloride ions?
-- Involved in the chloride shift which helps maintain the pH of the blood during gas exchange.
-- Acts as a cofactor for the enzyme amylase.
-- Involved in nerve impulses
33
Phosphate ions?
-- Important in photosynthesis and respiration reactions
-- It is needed for the synthesis for important biological molecules like nucleotides, ATP, phospholipids, calcium phosphate (strengthen bones )
34
Hydroxde ions?
--Affects the pH of substances.
35
What is the structural diffecence between alpha and beta glucose molecules?
The H group on the alpha glucose is above the ring.
36
What is the light microscope used to observe?
Whole cells and tissues
37
What is a transmission electrom microscope used to observe?
Organelles
38
What is a laser scanning confocal microscope used to observe?
An object at a certain depth within a cell
39
State what is meant by the resolution of a mcroscope
The ability to distinguish between two points in a microscope.
40
What guidelines must students follow to ensure they present their diagrams clearly and accurately?
-- Use a sharp pencil
-- Use ruled labelled lines
-- Do not shade
-- Make sure that the diagram fills up at least half of the page
-- Include a scale bar
-- When labelling make sure that the lines do not cross over each other
41
State some ways students can ensure that they can be confident in thier results
-- Do the investigation multiple times
-- Calculate the mean
-- Carry out a statistical test
-- Identify anomalies
42
Why is DNA replication described as semi-conservattive?
This is because after replication, each DNA strand has an original strand.
43
In which part of the cell will hypermethylation occur?
Nucleus
44
What is the term given to plants that are well adapted tp very dry conditions?
Xerophytic
45
How can you purify DNA?
- This reaction is called Precipitation Reaction.
-- Using onion as an example, blend the onion in a blender to break up the cell.
-- Make a solution of detergent, salt and distilled water.
-- Add the broken up cell to the beaker containing detergent mixture, then incubate at 60 degrees celcius for 15 minutes.
-- Put the beaker in a ice cold water bath to cool the mixture
-- Add protease enzymes to break up proteins and the proteins surrounding the DNA.
-- Add RNase enzymes to break up the RNA
-- Slowly drizzle cold ethanol down the side of the beaker containg the DNA-detergent mixture.
-- Leave for a few minutes, a white precipitate should form
46
When purifying DNA, what does the detergent in the detergent mixture do?
-- The detergent breaks down the cell membrane.
47
When purifying DNA, What is the purpose of the salt in the detergent mixture?
-- It binds to the DNA causing it to clump together
48
When purifying DNA, why do we incubate the DNA-detergent mixture in 60°C?
-- The high temperaure denatures the enzyme preventing them from working properly and breaking down the DNA
49
What process does DNA replicate by?
-- Semi-conservative DNA replication.
50
What is a mutation?
A mutation is a change to DNA base sequence which results which can alter to the 3D structure.
51
What is the process of DNA Self-Replication?
-- DNA helicase breaks the hydrogen bond between the two polynucleotide DNA strands. The helix unzips to forn two single strands.
-- Each orginal DNA strand acts as a template for a new strand. Free floating nucleotide strands, join to the exposed bases by complementart base pairing.
-- The nucleotide strand is joined together by DNA polymerase forming a sugar-phosphate backbone. Hydrogen bonds form between the new strand and the original strand. The strands twist to form DNA double helix.
-- Each DNA molecule contains one strand from the original DNA molecule and a new strand.
52
What is a gene?
A gene is a sequence of DNA nulcleotide that codes for a polypeptide.
53
Why does DNA have to undergo transcription and translation for protein synthesis?
-- DNA is found in the nucleus, and the organelles that make protein is located in the cytoplasm.
-- DNA is too large to move out of the nucleus so it first has to undergo transcription- a section of DNA is copied into mRNA
then translation- mRNA moves out of the nucleus to join up with ribosomes that syntehsises proteins.
54
What are the three features of the genetic code?
-- It is degenerate: there are more possile combinations of trplets than there are amno acids. This means that an amino acid can be cided for by more than one triplet.
-- It is non-overlapping: Each base triplet is read in threes separate from the triplet before and after it.
-- It is universal: The same base sequence that codes for a specific amino acid is sthe same in all othe rliving organism.
55
What are the monomer units of DNA called?
Nucleotides
56
what is the name of the bond present in the prrimary structure of a proten?
Peptide bonds
57
What are the features of a globular protein?
-- It is compact
-- It is round
-- It contains a prosthetic group
58
What role does RNA polymerase play in the production of an mRNA sequence?
It joins the mRNA strand together forming phosphodiester bond
59
Why is it important that the technique used for culturing microrganisms be aeseptic?
It prevents conatmination by micro-organisms
60
State a material that can be used as the sationary phase in thin layer chromotography
-- Silica gel
61
What are the importance of iron ions?
Iron ions are a component of haemoglobin which is an oxygen carrying molecule in red blood cells
62
What are the importance of phosphate ions?
Phosphate ions are a component of DNA and ATP
63
What is the test for a reducing sugar?
-- Add benedicts reagent and if a reducing sugar is present, a coloured preciitate forms.
-- The more the precipitate, the further the colour change. (bgyob)
-- A more accurate way of doing this is to filter the solution and weight the prcipitate.
64
Whhat is the test for a non-reducing sugar?
-- Add dilute hydrocloric acid and carefully heat it in a water bath that has been brought to boil.
-- Then add hydrogen carbonate.
-- Then just carry out teh benedicts test.
-- If the test is positve, a coloured precipitate forms.
65
What is the test for proteins?
-- The biuret test is used to test for proteins.
-- Firstly, a sample of the solution is placed in a test tube and subsequently an equal amount of NaOH is added.
-- Afterwards, a few drops of dilute copper (II) sulfate solution is added and gently mixed.
-- In the presence of a protein, the solution turns purple as an indicator of peptide bonds.
-- In the absence of protein, the solution remains blue
66
What are the structure of a protein?
Primary structure: This is the sequence of amino acids in a polypeptide chain.
Secondary structure: Hydrogen bonds form causing it to fold into alpha helix and beta pleate sheets.
Tertiary structure: The amino acid is coiled more forming more bonds in the process. More hydrogen binds form, disulfide bridges forms, ionic bonds and hydrophillic and hydrophobic inyeractions. This is the final 3D shape of the protein.
It can be globular or fibrous. Globular proteins such as enzymes are compact whereas fibrous proteins such as keratin are long and thus can be used to form fibres.
67
What is the buiret test?
-- The biuret test is used to test for proteins.
-- Firstly, a sample of the solution is placed in a test tube and subsequently an equal amount of NaOH is added. Afterwards, a few drops of -- dilute copper (II) sulfate solution is added and gently mixed.
-- In the presence of a protein, the solution turns purple as an indicator of peptide bonds.
-- In the absence of protein, the solution remains blue.
68
What is the test for lipids?
-- The emulsion test is used to test for lipids.
-- Shake the test substance with ethanol for about a minute then pour the solution into water.
-- If lipid is present, the solution turns milky
-- If lipid is not present, the solution stays clear.
69
What are the factors affecting the rate of enzyme-controlled reactions?
• Enzyme concentration – the rate of reaction increases as enzyme concentration increases as there are more active sites for substrates to bind to, however increasing the enzyme concentration beyond a certain point has no effect on the rate of reaction as there are more active sites than substrates so substrate concentration becomes the limiting factor.
• Substrate concentration – as concentration of substrate increases, rate of reaction increases as more enzyme-substrate complexes are formed. However, beyond a certain point the rate of reaction no longer increases as enzyme concentration becomes the limiting factor • Temperature – rate of reaction increases up to the optimum temperature, which is the temperature at which enzymes work at their maximum rate. Rate of reaction decreases above the optimum temperature
70
How do competitive inhibitoirs work?
Competitive inhibitors are similar in structure to the substrate molecule therefore they bind to the active site of the enzyme, decreasing its activity as they compete with substrate for the enzyme.
71
How do you reverse the change brought by competitive inhibiyors?
The higher the concentration of competitive inhibitor the lower the reaction rate. Increasing the substrate reverses the effect of competitive inhibitors by outcompeting them.
72
How do non-copetitive inhitors work?
Non-competitive inhibitor does not bind to the active site; it binds at another site on the enzyme known as the allosteric site. Binding of the non-competitive inhibitors changes the shape of the active site therefore preventing the binding of the substrate.
73
Can you reverse the effects brought by a non-competitive inhibitor?
74
What is diffusion?
Diffusion is the passive movement of small, non-polar lipid soluble molecules such as carbon dioxide and oxygen from an area of high concentration to an area of low concentration.
75
What is osmosis?
Osmosis is the diffusion of water molecules from an area of high water potential to an area of low water potential through a partially permeable membrane.
76
What is active transport?
Active transport can transport all types of molecules through carrier proteins from an area of low concentration to an area of high concentration. However, this process requires energy in the form of ATP
77
What are some factors that can affect the rate at which diffusion occurs?
-- Surface area
-- Diffusion distance
-- Diffusion gradient.
-- Temperature
78
What is ribosomes made out of?
It’s made up of proteins and RNA
79
What is the function of the vacuole?
-- Contains cell sap.
-- The membrane surrounding plant cell vacuoles is called the tonoplast.
-- They help to maintain pressure inside the cell and keep it rigid.
-- The vacuole is also involved in isolating unwanted chemicals in the cell.
80
What occurs during transcription?
1. At the initial point of a gene, RNA polymerase attaches to the DNA double-helix.
2. Hydrogen bonds between bases of DNA breaks to uncoil a segment of DNA thus exposing some of the bases.
3. Among the two strands of DNA, one is used as template for making mRNA copy.
4. Free RNA nucleotides are arranged beside exposed bases of DNA by RNA polymerase.
5. The base pairs of DNA pairs up with free RNA nucleotides following complementary base pairing.
6. Then these RNA nucleotides are joined by RNA polymerase forming RNA molecule.
7. Now RNA polymerase moves along the length of DNA to make a whole mRNA.
8. Once RNA polymerase completes its moving through DNA, it again recoils by forming the lost H-bonds.
9. RNA polymerase stops at a certain place in DNA called stop signal and finally detaches from DNA.
10. mRNA will come out of the nucleus through nuclear pores in eukaryotes and further steps of protein synthesis take place in cytoplasm.
81
What occurs during translation?
1. The mRNA, ribosome and tRNA all come together.
2. Ribosome attaches to mRNA and amino acids are carried by transfer RNA (tRNA) near to ribosomes.
3. tRNA molecule carrying amino acids and anticodon pairs with the first codon of mRNA .
4. Then second tRNA molecule attaches itself to mRNA in same manner.
5. A peptide bond is formed between amino acids on two different tRNA molecules. The first tRNA molecule leave its amino acid at this point.
6. This process continues till ribosome reaches the stop codon on mRNA, thus producing a chain of amino acids (polypeptide or protein).
7. The polypeptide chain moves away and leaves behind ribosome and then translation completes.
82
How do enxymes work?
-- Enzymes are biological catalysts.
-- They increase the rate of reactions by lowering the activation energy.
83
What are the limitations of the lock and key model?
● It does not easily explain how activation energy is lowered.
● It does not easily explain the role of competitive inhibitors.
● It does not easily explain the role of non-competitive inhibitors.
84
What are the advantages of the induced fit model?
● Can explain how the activation energy is lowered, the stretching and distorting of bonds or causing the closer orientation of reactive groups.
● Explain how non-competitive inhibitors can bind to a region away from the active site and change its shape so that substrate can no longer bind to the active site.
● Explains how competitive inhibitors can bind to the active site or other molecules with similar shapes to the substrate.
85
What are some factors affecting the rate of enzyme activity?
-- Temperature
● Increase in temperature increases kinetic energy.
● so more enzyme substrate complexes form.
● High temperatures cause denaturation, due to the breaking of breaking of bonds holding the tertiary structure together (H bonds/disulphide bridges/ionic bonds).
● Active site altered (changes shape) substrate cannot bind, no enzyme substrate complexes form.
-- pH
● Deviations from the optimum pH cause a decrease in enzyme activity.
● Small deviations change the charge at the active site and affect the binding of the substrate.
● Larger deviations can cause the hydrogen and ionic bonds holding the tertiary structure together to change and the enzyme denatures, meaning enzyme substrate complexes can no longer form.
-- Enzyme Concentration
● As enzyme concentration increases so will the rate: As there are more enzyme substrate complexes forming.
● At very high concentrations of enzyme the rate remains constant as substrate becomes the limiting factor Add more enzyme will cause rate to increase again.
-- Substrate Concentration
● As the substrate concentration increases, the rate increases because more substrate molecules can collide with enzyme molecules, so more reactions will take place.
● At higher concentrations the enzyme molecules become saturated with substrate, so there are few free enzyme molecules, so adding more substrate doesn't make much difference.
86
How do competitive inhibitors work?
● They have a similar shape to that of the substrate molecules.
● They compete with the substrate molecules to bind to the active site, but no reaction takes place.
● Instead of a reaction, they block the active site so no substrate molecules can fit in it.
● The level of activity inhibited depends on the relative concentrations of the inhibitor and the substrate.
● High concentration of the inhibitor means it will take up nearly all of the active sites and hardly any substrate will get to the enzyme.
● With a lower concentration, the chances of the substrate getting to an active site before the inhibitor increase.
● So, increasing the concentration of a substrate will increase the rate of reaction - up to a point.
87
How do non-competotive inhibitors work?
● They bind to the enzyme away from its active site.
● This causes the active site to change shape so the substrate molecules cannot bind to it.
● They don’t “compete” with the substrate molecules to bind to the active site because they are different shapes.
● Increasing the concentration of substrate doesn’t affect the reaction rate - enzyme activity is still inhibited.
88
How can molecule be transported?
● Simple diffusion.
● Facilitated diffusion.
● Osmosis.
● Active Transport.
● Co-transport.
89
Describe mitosis.
Mitosis is the type of cell division which produces two daughter cells that are identical from the parent cell.
90
Describe meiosis.
Meiosis is the type of cell division which produces daughter cells that is not identical to the parent cell, and contains half the amount genetic material as the parent cell.
91
What occurs at the G1 Checkpoint?
-- Cell size and protein reserves are assessed.
-- Determines whether all conditions are favourable for cell division to proceed.
-- Check for genomic DNA damage is done at the G1 checkpoint.
92
What happens at the G2 checkpoint?
-- The most important role of the G2 checkpoint is to ensure that all of the chromosomes have been replicated and that the replicated DNA is not damaged.
-- On detection of damage, the cell cycle is halted, and the cell attempts to either complete DNA replication or repair the damaged DNA.
93
What happens at the M checkpoint?
-- It determines whether all the sister chromatids are correctly attached to the spindle microtubules.
94
What occurs during prophase?
-- The nuclear envelope breaks down and the chromosomes lie free in the cytoplasm.
-- The chromosomes condense getting shorter and fatter
-- The centrioles move to opposite end of the poles forming spindle fibres
95
What are the phases of interphase?
-- G1 phase
-- S phase
-- G2 phase
96
What occurs during G1 phase?
cell grows bigger and replicates its organelles. A high amount of protein synthesis is taking place in order to build new organelles.
97
what occurs during S phase?
the cell replicates its DNA
98
What occurs during G2 phase?
the cell keeps growing until all of the organelles have duplicated.
99
What occurs during interphase?
Interphase - the cell prepares for mitosis by growing larger, replicating its organelles and synthesising new DNA (see above).
Once the DNA has replicated, each chromosome now consists of two sister chromatids, connected by a structure called the centromere. The mitochondria produce more ATP which will provide the energy for cell division.
100
What occurs during prophase?
-- The chromosomes condense (they become shorter and fatter) and the nuclear envelope breaks down.
-- The centrioles move to opposite poles of the cell and form spindle fibres.
101
What occurs during metaphase?
-- The chromosomes line up along the middle of the cell, attached to the spindle fibre by their centromere.
102
What occurs during anaphase?
-- The spindle contracts causing the centromere to split and the chromatids are pulled to opposite poles of the cell.
103
What occurs during telophase and cytokinesis?
-- The chromatis reach the end of the cell uncoiling (they become long and thin) and a nuclear envelope reforms around them, forming two new nuclei.
-- The cytoplasm divides (cytokinesis) and the plasma membrane pinches off to form two new, genetically-identical cells.
104
What occurs during Meiosis I?
Interphase: the DNA replicates so there are now two identical copies of each chromosome (referred to as chromatids).
Prophase I: chromatids condense and arrange themselves into homologous pairs (called bivalents). Crossing over occurs (see below). The nuclear envelope disintegrates and spindle fibres form.
Metaphase I: homologous chromosomes line up along the equator and attach to the spindle fibre by their centromeres.
Anaphase I: homologous chromosomes are separated
Telophase I: chromosomes reach opposite poles of the cell. Nuclear envelope reforms around the chromosomes. Cytokinesis results in the formation of two daughter cells.
105
What occurs during Meiosis II?
Prophase II: chromosomes condense, nuclear envelope disintegrates and spindle fibres form.
Metaphase II: chromosomes attach to the spindle fibre by their centromeres.
Anaphase II: sister chromatids are separated.
Telophase II: chromatids reach opposite poles of the cell. Nuclear envelope reforms and cytokinesis takes places. Four genetically unique daughter cells are produced.
106
How does meiosis increases genetic variation?
Meiosis increases genetic variation in two ways - crossing over and independent segregation.
107
What are stem cells?
-- Stem cells are unspecialised cells which have the ability to become specialised cells, such as heart cells or neurons
108
What is cell differentiation?
The process by which a stem cell is converted from unspecialised to specialised.
109
Totipotent Cells?
Totipotent cells have the ability to divide into any type of cell (including the extraembryonic cells which make up the placenta and umbilical cord).
110
Pluripotent cells?
Pluripotent cells can divide into any type of cell except the extraembryonic cells.
111
Multipotent cells?
these cells can divide into a handful of different cell types
112
Unipotent cells?
these cells can only divide into one type of cell
113
Types of specialised cells
-- Neutrophil
-- Epithelial cells
-- Sperm cells
-- Palisade cells
-- Root hair cells
-- Guard cells
114
What are some of the functions of cell membranes?
-- Acts as a barrier between areas
-- Involved in cell signalling
-- Site of chemical reaction
115
How do plants protect themselves from infection by a pathogen?
-- By producing callose
-- Leaf drop (abcission)
-- Necrosis
-- By producing antitoxins
116
Suggest why it is important to use a clone in certain experiments?
-- No genetic variation, this make the variable more controlable which in turn increases the validity of the result.
117
Why is asepsis important?
It prevents contamination.
118
List some abiotic factors that can be controlled when planting.
-- Light intensity
-- Light duration
-- Soil nutrients
-- Air pollution
-- Soil water content
-- Temperature
-- Wind speed
-- Rainfall
119
What is one valid concern about the genetic modification of bacteria?
-- antibiotic resistance
