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Stage 2 Biology > Cells as the Basis of Life (Tillie) > Flashcards

Cells as the Basis of Life (Tillie) Flashcards

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1
Q

What are cells?

A

Cells are the structural unit of living things, known as the “building blocks” that make up organisms, and they are also functional units as organisms are made up of many cells, therefore when we refer to what they do we also refer to cells

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2
Q

What is Cell Theory?

A

Cell Theory is a unifying concept as it unifies all living things as they are the basic structural unit and functional unit of life.

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3
Q

Describe Cell Theory

A

includes the idea that all cells come from a previous cell that contain hereditary information, all living things are complex and have organised structures, cells take in energy from their surrounding environment and use it, cell’s have an internal composition that is chemically different from external environment, and cells respond to stimuli, reproduce themselves and grow.

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4
Q

Describe what the cell membrane is?

A

The cell membrane, also called plasma membrane, separates the cell from its surroundings and controls the exchange of materials, including nutrients and wast, between the cell and its environment

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5
Q

Describe the fluid mosaic model?

A

The model proposes that the cell membrane is a fluid mosaic as it is composed of a phospholipid bilayer with protein molecules embedded in and through the layer at various point.
Fluid: as phospholipids are constantly moving
Mosaic: proteins embedded in membrane

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6
Q

What are the differences between prokaryotic and eukaryotic cells?

A
  • Size: prokaryotes are smaller in size compared to eukaryotes
  • DNA: the DNA is circular in prokaryotes and linear in eukaryotes
  • nucleus: there is no nucleus in prokaryotes and is a nucleus in eukaryotes
  • internal organisation: little internal organisation in prokaryotes and high level internal organisation in eukaryotes
  • location of chromosomes: DNA in prokaryotes is in cytoplasm, DNA in eukaryotes in nucleus
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7
Q

What is the structure and function of nucleus?

A

Structure: nucleus is composed of two membrane layers called the nuclear envelope and it contains nuclear pores lined with proteins
Function: controls the activity of the cell and stores genetic information (DNA)

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8
Q

What is the structure and function of the nucleolus

A

Structure: a circular region not bounded by membrane in the nucleus that is composed of DNA and proteins
Function: produces and assembles cell ribomosomes

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9
Q

What is the structure and function of mitochondria?

A

Structure: has an outer membrane and an inner membrane which is folded to form structures of cristae
Function: involved in the latter stages of aerobic respiration using O2 and glucose to release energy to be stored in ATP

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10
Q

What is the structure and function of chloroplast?

A

Structure: Only found in plants and are a type of plastid. It has 2 outer membranes and inside there is a system of flattened sacs called thylakoids which are arranged into stacks of grana (singular granum). Fluid called stroma surrounds the membrane out sacs
Function: photosynthetic pigment, chlorophyll, is stored in thylakoids to carry out photosynthesis

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11
Q

What is the structure and function of vacuole?

A

Structure: a fluid filled space bounded by a membrane. Most plants contain large central vacuole.
Function: maintaining balance of water and salt for the cell and is a place to store organic compounds such as proteins and sugars and inorganic compounds such as ions (potassium and chloride)

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12
Q

What is the structure and function of golgi body?

A

Structure: sticky of flattened sacs made of smooth membranes
Function: involved in the packing and secretion of proteins and carbohydrates manufactured by the cell

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13
Q

what is the structure and function of endoplasmic reticulum?

A

Structure: system of membranes that extends throughout the cytoplasm from the nuclear envelope to cell membrane. Forms intricate network of pathways
Function: involved in transport of materials
RER structure: attached ribosomes
Function: site of protein and membrane synthesis
SER: no attached ribosomes
Function: involved in metabolic processes such as lipid synthesis and carbohydrate metabolism

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14
Q

What is the structure and function of ribosomes?

A

Structure: made up of RNA and protein, and is enclosed by a membrane
Function: site of protein and membrane synthesis

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15
Q

What is the structure and function of lyosome

A

Structure: vesicle, membrane enclosed containing digestive enzymes
Function digests macromolecules

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16
Q

Describe what prokaryotic cells are

A

A single-cell organism that lacks a nucleus are other membrane bound organelles and belongs to domains of bacteria and archaea

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17
Q

Describe what eukaryotic cells are

A

An organism that possess a clearly defined nucleus and membrane bound organelles. They can range from single-cell organisms to complex multicellular organisms like animals and plants

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18
Q

What is the structure and function of the cytoskeleton?

A

Structure: network of fibres throughout cytoplasm, it is made up of three main components microfilaments, intermediate filaments and microtubules. The components are made up of protein moleules that can be assembled to form long filaments and hollow tubules.
Function: gives cell shape, involved in cell movement, holds organelles in place and provides cell strength

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19
Q

What is the structure of plant cells

A

Cell wall, cell membrane, nucleus, nucleolus, mitochondria, chloroplasts, vacuoles (large central), Golgi body, endoplasmic reticulum, ribosomes, lysosomes and cytoskeleton

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20
Q

What is the structure of animal cells

A

Cell membrane, nucleus, nucleolus, mitochondria, vacuoles (small), Golgi body, endoplasmic reticulum, ribosomes, cytoskeleton

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21
Q

What do cells require?

A

Cells require inputs of suitable forms of energy, including light energy or chemical energy in complex molecules

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22
Q

What are autotrophs?

A

Organisms that make the energy rich compounds they need from simple inorganic susbstance, and energy for synthesis reactions, commonly from sun, using physical energy

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23
Q

What are heterotrophs

A

Organisms that cannot make energy rich compounds their self, therefore they rely on the intake of nutrition from other sources of organic carbon, using chemical energy

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24
Q

What is photosynthesis and why is it important?

A

Photosynthesis is the process when light energy is used to synthesis complex organic compounds from simple organic substances. It is a fundamental chemical process that provides photsynthic autotrophs with food and also takes carbon dioxide out of the atmosphere by replacing it with oxygen

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25
Q

What is the equation for photosynthesis

A

6CO2 + 6H2O - light/chlorophyll –> C6H12O6 +6O2

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26
Q

what is the chemical equation for aerobic respiration

A

C6H12O6 +6O2 ——–> 6CO2 + 6H2O

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27
Q

What is the worded equation for aerobic respiration

A

Glucose + Oxygen —–> Carbon dioxide + water

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28
Q

What is the worded equation for photosynthesis

A

Carbon dioxide + water —–> Glucose + oxygen

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29
Q

What is anerobic respiration?

A

respiration that does not require oxygen to generate energy from glucose

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30
Q

Why is anerobic repsiration important in plants and yeast

A

to provide them energy when oxygen is unavailable

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31
Q

why is aerobic respiration important

A

as it converts oxygen and food (glucose) into energy that eukaryotes require to survive

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32
Q

what is the worded equation for fermentation in plants and yeast

A

glucose ——-> ethanol + carbon dioxide

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33
Q

What is chemical equation for fermentation in plants and yeast

A

C6H12O6 ———> 2C2H5OH + 2CO2

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34
Q

why is anerobic respiration important in animals

A

to produce energy for the cells when undergoing exercise, ensuring that blood is being delivered to cells under stress

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35
Q

What is the worded equation for fermentation in animals

A

glucose ——-> lactic acid

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36
Q

What is the chemical equation for fermentation in animals

A

C6H12O6 ——->2C3H6O3

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37
Q

How much energy is released through aerobic respiration

A

36 ATP yield per glucose

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38
Q

how is energy released in aerobic respiration

A

Through the breakdown of glucose in the presence of oxygen as the energy in the reactants is greater than the energy in the products.

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39
Q

how much energy is released in fermentation

A

2 ATP yield per glucose

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40
Q

how is energy released in anerobic respiration

A

through the breakdown of glucose molecule through glycolysis, in which a glucose molecule is broken down into two pyruvate molecules, releasing electrons in the process and producing two ATP molecules, the energy of the cells.

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41
Q

What happens to energy when new bonds are formed

A

The formation of chemical bonds releases energy

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42
Q

what happens to energy when chemical bonds break

A

When the chemical bonds that hold atoms together are needed to be broken energy is required

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43
Q

is energy required or released when chemical bonds are broken

A

Required

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44
Q

is energy required or released when new bonds are formed

A

Released

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45
Q

why do cells require input of matter

A

To provide them with the materials needed to grow and carry out life processes

46
Q

why do cells require output of matter

A

remove cell waste

47
Q

What are the inputs in autotrophs

A

Oxygen, carbon dioxide, nitrates, nitrites, phosphates, calcium, inorganic nutrients

48
Q

What are the outputs in autotrophs

A

Oxygen, carbon dioxide, ethanol

49
Q

What are the inputs in heterotrophs

A

Oxygen, nitrates, nitrites, phosphates, calcium, inorganic nutrients, organic compound

50
Q

What are the outputs in heterotrophs

A

Carbon dioxide, lactic acid, urea

51
Q

What is diffusion

A

Occurs through the membrane bilayer where movement of one substance from an area of high concentration to an area of lower concentration until equilibrium is reached, the transport is passive

52
Q

What is facilitated diffusion

A

Substances moved from high concentration to lower concentration through the involvement of proteins embedded throughout membrane, passive transport

53
Q

what is osmosis

A

The diffusion of water through passive transport to maintain salt and water balance and cell shape

54
Q

what is active transport

A

Is the movement of substances against the concentration gradient with the input of energy and carrier protein

55
Q

what is endocytosis

A

When cells take in particles or large molecules by enclosing them in a membranous vacuole, being two main types phagocytosis (intake of particles when the membrane invaginates in the vicinity of the particle enclosing it into a vacuole then breaks away from membrane into cytoplasm) and Pinocytosis (intake of liquids or large molecules unto tiny vesicles that form on cells cerface

56
Q

what is exocytosis

A

Is the secretion of material produced by the cell involving the packing of materials into a vesicle that migrates to the membrane to be fused and release contents)

57
Q

How does the structure of a membrane facilitate different processes of movement

A

The phospholipids of plasma membranes are amphipathic: they have both hydrophilic (water-loving) and hydrophobic (water-fearing) regions. The hydrophobic core of the plasma membrane helps some materials move through the membrane, while it blocks the movement of others.

58
Q

What is the role of transport proteins, including channel and carrier proteins

A

Channel proteins: bind certain ions/molecules and Carrie’s them through membrane
Carrier proteins: change shape as they bind to specific molecules to assist in transporting them from one side of the membrane to another

59
Q

How is the exchange of materials affected by surface-area-to-volume ratio

A

As cell size increases its surface area to volume ration decreases, meaning less relative surface area is being exposed to the environment compared to cell volume
Thus if the cell has to low of a surface area to volume ratio the exchange of material with extra cellular space decreases

60
Q

How is the exchange of materials affected by concentration gradients

A

In diffusion and osmosis particules move with the concentration gradient from high to low, thus the greater the difference in concentration the rate of exchange increases

61
Q

How is the exchange of materials affect the physical and chemical nature of the materials being exchanged

A

The type of particle exchanged is important as small uncharted particles such as O2 and CO2 can pass through the membrane easily via diffusion and larger/charged particles such as glucose and ions require assistance from channel proteins, carrier proteins or endocytosis

62
Q

What is cell metabolism and why is important

A

As cells need to synthesis a large number of compounds such as proteins, carbohydrates, lipids, and nucleic acids and break down compounds such as glucose provide

63
Q

What are biochemical processes in cells influenced by

A

by the nature and arrangement of internal membranes and the presence of specific enzymes

64
Q

how does the structure of the internal membranes of mitochondria facilitate biochemical processes

A

The cristae provide large surface area for the attached ent of enzymes such as ATP synthesis that plays an important role in aerobic respiration. The folded inner membranes of the mitochondria are the main site of ATP production

65
Q

how does the structure of the internal membranes of chloroplast facilitate biochemical processes

A

Thylakoids contain photosynthetic pigments that are able to trap light energy for photosynthesis

66
Q

Explain the importance of regulated steps in metabolic pathways

A

Ensures the reaction does not occur too rapid, preventing the cell burning up and maximises the amount of energy stored in ATP molecules during the process

67
Q

Explain the importance of steps producing intermediate compounds in metabolic pathways

A

Allows a starting point for other reactions

68
Q

Why, at each step, does energy release in metabolic pathways

A

So energy can be trapped by energy molecules like ATP

69
Q

Why are specific enzymes required at each step in metabolic pathways

A

To decrease the time chemical processes occur as if not them chemical processes would occur to slowly or not at all

70
Q

What are biochemical processes in cells influenced by

A

Presence of enzymes, thus affected by temperature, pH, the presence of inhibitors, concentration of reactants and concentration of enzyme

71
Q

What are possible benefits of the chemicals used by humans

A
  • development of drugs and vaccines
  • cleaning agents (remove microorganisms from surfaces
  • preservatives
  • biotechnology applications
    Etc..
72
Q

What are the possible harmful effects of chemicals used by humans

A

Harmful effect depends on type of chemical, exposure level, exposure duration and individual susceptibility
- respiratory issues
- carcinogens
- reproduction issues
- skin and eye irritation

73
Q

Why does the amount of DNA double in a cell before division

A

In multicellular organisms cells need to be continually replaced, thus each of the new cells must relieve a copy of the genetic information stored in DNA. This caused DNA in a cell to be replicated before the cell divides to ensure that when the cell divides each new cell will recieve the same amount of DNA containing identical information

74
Q

describe and explain the process of binary fission in prokaryotes

A
  • The Dna is formed into a single double helix ring called nucleotide
  • DNA duplicated before division
  • both nucleotides attach to the cell membrane by proteins near the middle of the cell
  • the cell grows and the loops of DNA (chromosomes) move apart
  • the cell pinches across the equator giving rise to two identical daughter cells
75
Q

describe and explain the process of mitosis in eukaryotes

A

Mitosis is the replication of eukayotic cells that doesnt involve gametes
- Interphase: this is where cells spend 90% of their time, with cells growing and chemical reactions occurring, and metabolic activity. During this phase the chromosomes replicate but do NOT condense and are still present in loosely packed chromatin, the centrioles also duplicate forming 2 pairs that line up just out side of nucleus
- Prophase: in prophase there are 2 stages early prophase and late prophase. In early chromosomes begin to condense and become visible as loose X-shapes (sister chromatids joined by centromere). In late (prometaphase_ the nuclear membrane fragments, chromosomes condense furher and the microtubels of mitotic spindle invade there area of the nucleus to connect to the kinetochore on centromere region
- Metaphase: the centriole pairs move to opposite ends of the cell, the chromosomes convene to the metaphase plate, centromeres are aligned and the chromosomes lie with long aces at roughly right angles o the spindle, then microtubels of spindles connect to centromere
- Anaphase: this is where chromtids move apart, with each crhomatid. The spindle pulls on the chromosomes towards poles (end of cell) and at the same time poles of the cell move futher apart.
- Telophase: the polar fibres extend the cell further and the daughter nuclei begins to form from the fragments of the parent nuclear membrane, cleavage furrow forms and the nucleoli reappears and the chromatin fibre uncoils
- Cytokinesis: where the division of the cytoplasm occurs along the cleavage furrow which pinches the cell in two.

76
Q

What is glycolysis

A

A metabolic process where glucose is broken down under anerobic conditions through a series of small steps through the metabolic pathway in the cytoplasm, where a specific enzyme catalyses each step, with intermediate compounds produced by enzymes. In glycolysis 2 ATP molecules are used to turn glucose into 2 pyruvates which causes 4 ATPs to be produced, and a net gain of 2 as 2 ATPs were used in the start of reaction.

77
Q

What is the energy pathway of glycolysis

A

Each step in glycolysis is regulated, with each step being catalysed by a specific enzyme. In each step there is an intermediate compound produced that is converted to the next intermediate compound . Thus the step conversion of glucose to pyruvate enables the cell to control the process, minimising rapid reactions and maximise amount of energy stored in ATP molecule in the process.

78
Q

What is a diploid cell

A

Two chromosomes of the same type make up an homologous pair, a cell that contains homologous chromosomes os called diploid cell.

79
Q

What is a haploid cell

A

Cells that have only one chromosomes from each homologous pair.

80
Q

What is asexual reproduction in eukaryotes

A

it is the propagation of an organisms without fertilisation, meaning genetically identical copies of the parent cell is produced, with it done through mitosis

81
Q

Describe the formation of ATP from ADP and Pi

A

ATP synthesis primarily occurs in the mitochondria, with a small amount in the cytoplasm in eukaryotes, where an inorganic phosphate is added to APD with the energy to add the third phosphate group coming from respiration. It can be summerised by this equation: APD+ Pi + energy ——> ATP

82
Q

Describe the conversion of ATP to ADP and Pi which releases energy for some metabolic reactions

A

ATP molecules have three phosphate groups therefore when reacted with water a process called ATP hydrolysis occurs with the bond between the second and third phosphate group breaking to form APD and Pi plus a net energy that the cell uses to work. It can be summarised by this equation:
ATP ——> ADP + Pi + energy

83
Q

describe the phases of meiosis in eukaryotic cells

A

in meiosis there is two consecutive cell division called meiosis 1 and meiosis 2.
Meiosis 1
this is a reduction processes where its purpose is to halve the chromosome number.
- Interphase: there is a pair of homologous pairs in the diploid parent cell, the chromosomes are duplicated, with now there being a pair of duplicated homologous chromosomes with sister chromatids, causing a diploid cell with duplicated chromosomes.
- Prophase: the nuclear envelope is broken and the chromosomes begin condensing and each pairs with it homolog. The homologs align themselves gene by gene and allow crossing over to occur, where the dna molecule of nonsister chromtids are broken by an enzyme causing fragments to rejoing and form new combinations of alleles. At the same time centrosomes begin producing spindle fibres that attach to the centromeres of each homolog.
Metaphase 1: pairs of homologous chromosomes are arranged at the metaphase plate through independent assortment. both chromtids of the homolog are attached to spindle fibres at opposite ends.
Anaphase 1: the homologs move toward opposite ends of the cell
Telophase 1: chromosomes move further apart and the nuclear membrane reforms from the parent cells fragments
Cytokinesis 1: a cleavage furrow forms that pinches the cell into 2, creating 2 haploid daughter cells.
Meiosis 2
- prophase 1: spindle apprapatus forms, chromosomes duplicate with each still composed of two sister chromatids.
- Metaphase 2: the chromosomes are positioned at the metaphase and the centromeres are attached to spindle fibres from opposite ends
- Anaphase 2: the sister chromatids separate and move toward opposite ends of the cell
- Telophase 2: the nuclei forms and the chromosomes begin decondensing
- Cytokinesis: the cell divides into two forming four haploid cells

84
Q

explain why products of meiosis are haploid cells and contain a single set of chromosomes

A

when combined with other gamete through random fertilisation the diploid number is restored

85
Q

why is crossing over and independent assortment important

A

increase genetic variation which significant in evolution when conditions in environment change genetic variation means more chance of offspring surviving, if all the same variation all will either survive or not

86
Q

how is the diploid number restored

A

through random fertilisation

87
Q

compare the products of meiotic and mitotic cell division

A

meiosis produces four cells and reduces the number of chromosome set from diploid (2) to haploid (1), produces genetically different cells from parent cell and each other
Mitosis produces 2 daughter cells that are genetically identical to parent and another, diploid number stays the same

88
Q

why is there more genetic variation in the products of sexual production compared to asexual production

A
89
Q

describe the stages in cell cycle (include checkpoints)

A

4 phases
G1, G2, S = interphase
M = mitosis and cytokinesis
- G1: cell is growing and carrying out cell functions
- G1 checkpoint: checks for cell growth, DNA damage, and that the cell has the resources it needs
- S: DNA is replicated
- G2: further preparation for cell division and cell growth
- G2 checkpoint: checks for cell growth, DNA replicated correctly and cell has the nutrients it needs
- M: mitotic division and cytokinesis
- M Checkpoint: checks at metaphase for correct chromosome alignment and spindle attachment

90
Q

role of hormones in regulating cell division

A
  • hormose is released by a signal cell and attaches to specific cell membrane receptors which contain a complementary #D shape to hormose on a target cell
    bidning leads to transcription and translation within cell to produce gene product that stimulates or inhibits cell division
91
Q

explain the effect of carcinogens on cell division

A

affects the cells ability to participant in cell cycle correctly as they disable the checkpoints meaning now growth factors are required to move from one checkpoint to the next, and in some cases cancer cells have the ability to secrete growth hormones which cause blood vessels to direct over to them away from healthy cells

92
Q

Describe 3 techniques of cell culture

A

SPRAY ON SKIN: healthy sample of skin cells from individual are collected and immersed in an enzyme solution to form a suspension liquid. The liquid includes keratinocytes, fibroblasts and melanocytes, which are cell types that are involved in wound healing. Then the suspension liquid is sprayed onto the burn wound, providing even and broad distribution of living cells across whole of wound.
- VACCINCE PRODUCTION: using cell lines to manufacture vacines such as influenza vaccine to test for drug efficancy, optimal dosage and side effects
- CANCER RESEARCH: looking at gene controll, changes in cell structure and function over time

93
Q

discuss the limitations and applications of the contemporary examples of cell culturing

A

Limitations
- cost
- time consuming
- contamination

Advantages
- millions grow in small space
- detect mutations and the organisms carrying them
- study mutant cells lacking enzyme
- avoid ethical issues

94
Q

What is the krebs cycle

A

Then the products from glycolysis go through the Krebs Cycle in the mitochondria, with enzymes again catalysing each step, and intermediate compounds produced. The Krebs cycle allows further breakdown of pyruvate while also releasing CO2 as a byproduct.

95
Q

what is electron transport chain

A

This cycle then results in the oxidative phosphorlyation electron transport where electrons are transferred across electron transport chain and water is produced as a byproduct.

96
Q

Effect of cyclin on mitosis

A

an increase of cyclin stimulates mitosis as the MPF increases stimulating mitosis through prophase and metaphase

97
Q

what regulates cell cycle

A

two proteins involved: cyclin and cdk
- cdk is a specifically an enzyme protein and cyclin binds to cdk at active site
- different forms of cyclin bind to cdk at cell cycle, thus different cyclin rise and fall throughout cell cycle. The rising and falling will determine if the cell moves to next cell cycle phase

98
Q

what happens if cell doesnt meet checkpoint requirements

A

if the reason can be fixed cell pauses in the phase until has the resources to fix issue
if not cell undergos apoptosis

99
Q

what causes uncontrolled division

A

a change in DNA sequence in a specific gene called protoncogenes which can turn into oncogenes. oncogenes cause cancer as cell division accelerates, which can be passed on in subsequent generations

100
Q

what regulates cell cycle progression

A

Cyclins, Cdks and tumour suppressors

101
Q

what is the role of cyclin in cell regulation

A

a protein that flucates in concentration to regulate progression in cell cycle phases. An increase in cyclin levels stimulates mitosis by forming the mitosis promoting factor

102
Q

What is the mitiosis promoting factors (MPF)

A

a complex of proteins including cyclin and Cdk that triggers cell progression from the G2 phase to M phase

103
Q

How does an increase in cycle levels affect mitiosis

A

an increase in cyclin levels leads to the formation of more MPF, the MPF stimulates mitosis through the prophase and metaphase

104
Q

Three conditions necessary for successful cell culturing

A

sterile conditions to prevent infection of cells by microorganisms
temperature - ensure enzyme working to opyimal effeciency to maximise rate of enzyme controlled reactions for max cell growth
Nutrients - sugars amino acids as they are the basic building clocks for cellular growth and reproduction

105
Q

explain how independent assortment contributes to variation

A

during meiosis 1 homologous pairs line up independently on other pairs, these separate into new combinations of maternal and paternal chromosomes, creating variation

106
Q

Explain how crossing over contributes to variation

A

it is the reciprocal exchange of segments of genetic material of nin sister chromatids, this results in maternal and paternal genes to mix leading to new combinations of genes in the gamest produced thus causing varaiation in offspring

107
Q

differences between binary fission and mitosis

A

spindle formed in mitosis not in binary fission
chromosomes attach to spindle in mitosis but attach to cell membrane in binary fission
nuclear membrane formed in mitosis
linear chromosomes in mitosis and signular circular chromosome in binary fission

108
Q

explain how the inhibition of cellular respiration would effect active transport

A

cellular respiration is the breakdown of glucose to release energy that is used to resynthesis ATP, which is the immediate source of energy for the cell for processes for active transport. Thus the inhibition of cellular respiration means less ATP production and therefore decrease in active transport

109
Q

how is the energy stored in ATP released for use

A

ATP converted to APD and phosphate, the breaking of the bonds between last two phosphates releases energy used for cellular respiration

110
Q

why is less energy released in anerobic respiration

A

because in aerobic respiration glucose in almost completely broken down into carbon dioxide and water releasing large proportions of energy from the breaking of chemical bonds, whereas in anerobic respiration glucose is partially broken down into lactic acid or ethanol therefore it releases smaller quantity of energy

Stage 2 Biology (3 decks)

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