Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOLOGY SL IBDP > TOPIC 1 - CELL BIOLOGY > Flashcards

TOPIC 1 - CELL BIOLOGY Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

The 3 ideas of cell theory

A
  1. Living organisms are composed of cells (or cell products)
  2. The cell is the smallest unit of independent life
  3. Cells can only arise from pre-existing cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

3 Examples of cells that do not follow cell theory.

A

Striated muscle fibres
Aseptate fungal hyphae
Giant Algae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why does Striated muscle fibres not follow cell theory? (2)

A
  • Consists of very ling fibres (>300mm)

- Consists of multiple nuclei, despite being surrounded by a single continuous plasma membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why does Aseptate fungal hyphae not follow cell theory? (1)

A
  • Consists of a thread like structure called hyphae separated in cells by internal walls called septa.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why does Giant Algae hyphae not follow cell theory? (2)

A
  • Grow very large in size.

- Challenges that idea that larger organisms are always made of many microscopic cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the functions of life?

A

Metabolism – Undertake essential chemical reactions.
Reproduction – Producing offspring either sexually or asexually.
Sensitivity – Responsive to internal and external stimuli
Homeostasis – Maintain a stable internal environment
Growth – Move and change shape or size
Respiration –
Excretion – Removal of waste products
Nutrition – Exchange materials and gases with the environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Surface area : volume ratio (4)

A
  • The larger the cell the more energy is needed to sustain essential functions. (Rate of metabolism).
  • The larger the membrane surface the more material movement. (Rate of material)
  • If metabolic rate exceeds rate of exchange the cell will die.
  • This is why cells divide and remains small to maintain high SA:Vol Ratio.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is gene packaging? (4)

A

DNA is packaged with proteins to form chromatin in the nucleus.
• Active genes are loosely packed as euchromatin
• Inactive genes are packed tight as heterochromatin

Differentiated cells will have different regions of DNA packaged according to their function.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is cellular differentiation? (3)

A
  • Differentiation involves the expression of some genes and not others in the cell’s genome (i.e. selective gene expression)
  • The activation of different genes within a given cell will cause it to develop differently from other cells (i.e. cell specialisation)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are stem cells?

A

When a cell differentiates and becomes specialised, it loses its capacity to form alternative cell types

Stem cells are unspecialised cells that have two key qualities:

  1. Self Renewal – They can continuously divide and replicate
  2. Potency – They have the capacity to differentiate into specialised cell types
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Different types of stem cells? (3)

A
  • Embryo
  • Umbilical Cord Blood
  • Adult Tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are stem cells used for? (3)

A

Stem cells are necessary for embryonic development as they are an undifferentiated cell source from which all other cell types may be derived

As these tissues cannot be regenerated or replaced, stem cells have become a viable therapeutic option when these tissues become damaged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Therapeutic Examples of Stem Cells: (3)

A

1) Stargardt’s disease - Macular degeneration: Replace defective retinal cells
2) Parkinson’s disease - Death of nerve tissue: Replace damaged nerve cells
3) . Leukaemia - Cancer of the blood: Replacement of bone marrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Stem Cell Therapy: (6)

A

Stem cells can replace damaged or diseased cells with healthy ones.
The therapeutic use of stem cells involves:
• Harvesting stem cells from appropriate sources
• Using biochemical solutions to trigger cell differentiation
• Surgically implanting new cells into patient’s own tissue
• Suppressing the host immune system to prevent rejection
• Monitoring new cells to ensure they do not become cancerous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the four main types of stem cells and their definitions?

A
  • Totipotent – Can form any cell type, as well as extra-embryonic tissue
  • Pluripotent – Can form any cell type (e.g. embryonic stem cells)
  • Multipotent – Can differentiate into closely related cell types
  • Unipotent – Cannot differentiate, but are capable of self-renewal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How are stem cells used to treat Stargardt’s disease?

A

Replace defective retinal cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How are stem cells used to treat Leukaemia?

A

Replacement of bone marrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How to calculate magnification?

A

M=I/A

Magnification = Image Size / Actual Size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Comparison of light microscope and an electron microscope

A

Light Microscopes:

Use lenses to bend light and magnify images by a factor of roughly 100-fold
Can be used to view living specimens in natural colour
Chemical dyes and fluorescent labelling may be applied to resolve specific structures

Electron Microscopes:

Use electromagnets to focus electrons resulting in significantly greater magnifications and resolutions
Can be used to view dead specimens in monochrome (although false colour rendering may be applied)
Transmission electron microscopes (TEM) pass electrons through specimen to generate a cross-section
Scanning electron microscopes (SEM) scatter electrons over a surface to differentiate depth and map in 3D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Prokaryotic cellular structure (7)

A
  • No Nucleus
  • Belong to the kingdom Monera.
  • A single, circular DNA molecule.
  • 70s Ribosomes
  • Pili
  • Flagella
  • Plasmids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Eukaryotic cellular structure and function: (8)

A
  • 80S ribosomes – Responsible for protein synthesis (translation)
  • Nucleus – Stores genetic information (site of transcription)
  • Mitochondria – Site of aerobic respiration (ATP production)
  • Endoplasmic reticulum – Transports materials between organelles
  • Golgi complex – Sorts, stores, modifies & exports secretory products
  • Centrosomes – Involved in cell division (mitosis and meiosis)
  • Chloroplasts – Site of photosynthesis (plant cells only)
  • Lysosomes – Breakdown of macromolecules (animal cells)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Animal vs Plant cell: (6)

A 
Animal Cells:
•  No chloroplast
•  No cell wall
•  No plasmodesmata
•  Temporary vacuoles
•  Cholesterol present in the cell membrane
•  Glucose → glycogen
Plant Cells:
•  Have chloroplast
•  Cell wall (cellulose)
•  Plasmodesmata
•  Large central vacuole
•  No cholesterol in the cell membrane
•  Glucose → starch
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Prokaryotic cellular division (6)

A

Prokaryotes divide by the process of asexual reproduction known as binary fission.
The process is:
• The circular DNA is copied
• The DNA loops attach to the membrane
• The cell elongates, separating the loops
• Cytokinesis occurs to form two cells

DNA Replication - > Cell Growth - > Cytokinesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is in the fluid mosaic plasma membrane model? (7)

A
  • Phospholipids
  • Channel Protein
  • Peripheral Protein
  • Integral Proteins
  • Carrier Protein
  • Cholesterol
  • Glycoprotein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Definition of Fluid Mosaic?

A
  • Fluid – the phospholipid bilayer is viscous and individual phospholipids can move position
  • Mosaic – the phospholipid bilayer is embedded with proteins, resulting in a mosaic of components
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the 3 main components of a Plasma Membrane and their function?

A
  • Phospholipids – Form a bilayer with phosphate heads facing outwards and fatty acid tails facing inwards
  • Cholesterol – Found in animal cell membranes and functions to improve stability and reduce fluidity
  • Proteins – May be either integral (transmembrane) or peripheral and serve a variety of roles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Structure of phospholipid bilayer? (3)

A
  • Consist of a polar head (hydrophilic) composed of a glycerol and a phosphate molecule.
  • Consist of two non-polar tails (hydrophobic) composed of fatty acid (hydrocarbon) chains
  • Because phospholipids contain both hydrophilic (water-loving) and lipophilic (fat-loving) regions, they are classed as amphipathic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Phospholipid Bilayer: Arrangement in Membranes (2)

A
  • Phospholipids spontaneously arrange into a bilayer
  • The hydrophobic tail regions face inwards and are shielded from the surrounding polar fluids, while the two hydrophilic head regions associate with the cytosolic and extracellular fluids respectively
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Properties of the Phospholipid Bilayer: (4)

A
  • The bilayer is held together by weak hydrophobic interactions between the tails
  • Hydrophilic / hydrophobic layers restrict the passage of many substances
  • Individual phospholipids can move within the bilayer, allowing for membrane fluidity and flexibility
  • This fluidity allows for the spontaneous breaking and reforming of membranes (endocytosis / exocytosis)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Integral proteins are…

A

…are embedded with proteins, which may be either permanently or temporarily attached to the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Peripheral proteins are…

A

…are temporarily attached by non-covalent interactions and associate with one surface of the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Functions of Membrane Proteins and function? (JETRAT)

A
  • Junctions – Serve to connect and join two cells together
  • Enzymes – Fixing to membranes localises metabolic pathways
  • Transport – Responsible for facilitated diffusion and active transport
  • Recognition – May function as markers for cellular identification
  • Attachment – Attachment points for cytoskeleton and extracellular matrix
  • Transduction – Function as receptors for peptide hormones
33
Q

Membrane Protein Functions: (6)

A

1) Intercellular Joining
2) Enzymatic Activity
3) Transport (active/passive)
4) Cell - Cell Recognition
5) Attachment
6) Signal Transduction

34
Q

What is cholesterol?

A

Cholesterol is a component of animal cell membranes, where it functions to maintain integrity and mechanical stability.

35
Q

Why is cholesterol absent in plant cells? (1)

A

because the plasma membrane is surrounded and supported by a rigid cell wall made of cellulose.

36
Q

What type of molecule is cholesterol?

A

Cholesterol is an amphipathic molecule — meaning it has both hydrophilic and hydrophobic regions

37
Q

What is cholesterol function in phospholipid bilayer? (4)

A
  • Cholesterol functions to immobilise the outer surface of the membrane, reducing fluidity
  • It makes the membrane less permeable to very small water-soluble molecules that would otherwise freely cross
  • It functions to separate phospholipid tails and so prevent crystallisation of the membrane
  • It helps secure peripheral proteins by forming high density lipid rafts capable of anchoring the protein
38
Q

Why was the fluid-mosaic model not accepted? (5)

A

When viewed under a electron microscope, membranes appear ‘trilaminar.’

• Trilaminar = 3 layers (two dark outer layers and a lighter inner region)

Membrane proteins were discovered to be insoluble in water (indicating hydrophobic surfaces) and varied in size

Fluorescent antibody tagging of membrane proteins showed they were mobile and not fixed in place

Freeze fracturing was used to split open the membrane and revealed irregular rough surfaces within the membrane

39
Q

What did Danielli and Davison propose?

A

Proposed a model whereby two layers of protein flanked a central phospholipid bilayer

40
Q

Basic Structure of a phospholipid bilayer: (4)

A
  • A polar organic molecule (e.g. choline, serine)
  • A phosphate group
  • A glycerol molecule (replaced by sphingosine in sphingomyelin)
  • Two fatty acid tails (may be saturated or unsaturated)
41
Q

Importance of cholesterol in phospholipid bilayers: (3)

A

Cholesterol acts as a bi-directional regulator of membrane fluidity

  • At high temperatures it stabilises the membrane and raises the melting point
  • At low temperatures it intercalates between the phospholipids and prevents clustering
42
Q

Passive Transort:

A

Passive transport involves the movement of material from high concentration ⇒ low concentration and does not require energy to do so. (ATP Hydrolysis)

43
Q

Active Transport:

A

Active transport involves the movement of materials from low concentration ⇒ high concentration requiring energy such as ATP hydrolysis to move against the gradient.

44
Q

What are the 7 modes of transport across the cellular membrane

A 
Diffusion
Osmosis
Active Transport
Facilitated Diffusion
Endocytosis 
Exocytosis
Movement of Vesicles Within the Cell
45
Q

Diffusion: (3)

A
  • Diffusion is the net movement of molecules from a region of high concentration to a region of low concentration.
  • It is passive.
  • Small and non-polar molecules can freely diffuse across cell membranes.
46
Q

The rate of diffusion can be influenced by a number of factors, including: (3)

A
  • Temperature (affects kinetic energy of particles in solution)
  • Molecular size (larger particles are subjected to greater resistance within a fluid medium)
  • Steepness of gradient (rate of diffusion will be greater with a higher concentration gradient)
47
Q

Osmosis:

A

Osmosis is the net movement of water molecules across a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration (until equilibrium is reached)

48
Q

Facilitated Diffusion: (2)

A
  • Facilitated diffusion is the passive movement of molecules across the cell membrane via the aid of a membrane protein
  • This process is mediated by two distinct types of transport proteins – channel proteins and carrier proteins
49
Q

Active Transport: (3)

A

Active transport uses energy to move molecules against a concentration gradient
This energy may either be generated by:
- The direct hydrolysis of ATP (primary active transport)
- Indirectly coupling transport with another molecule that is moving along its gradient (secondary active transport)

50
Q

What is Endocytosis?

A

The process by which large substances enter the cell without crossing the membrane

51
Q

What is Exocytosis?

A

The process by which large substances (or bulk amounts of small substances) exit the cell without crossing the membrane

52
Q

What are the 3 main types of passive transport?

A

Simple diffusion – movement of small or lipophilic molecules (e.g. O2, CO2, etc.)
Osmosis – movement of water molecules (dependent on solute concentrations)
Facilitated diffusion – movement of large or charged molecules via membrane proteins (e.g. ions, sucrose, etc.)

53
Q

What are the 2 main types of active transport?

A
  • Primary (direct) active transport – Involves the direct use of metabolic energy (e.g. ATP hydrolysis) to mediate transport
  • Secondary (indirect) active transport – Involves coupling the molecule with another moving along an electrochemical gradient
54
Q

What are the 2 main types of active transport?

A
  • Primary (direct) active transport – Involves the direct use of metabolic energy (e.g. ATP hydrolysis) to mediate transport
  • Secondary (indirect) active transport – Involves coupling the molecule with another moving along an electrochemical gradient
55
Q

What are the two types of Endocytosis and the definitions?

A

Phagocytosis – The process by which solid substances are ingested (usually to be transported to the lysosome)

Pinocytosis – The process by which liquids / dissolved substances are ingested (allows faster entry than via protein channels)

56
Q

What are the 3 ways osmosis can be measured?

A
  • Hypertonic: High solute concentration (gains water)
  • Hypotonic: Low solute concentration (loses water)
  • Isotonic:Samesoluteconcentration(nonetflow)
57
Q

What are the 2 properties of cell membranes?

A
  • Semi-permeable (only certain things can cross)

* Selective (membranes can regulate material passage)

58
Q

What are the 2 types of membrane transport?

A
  • Passive (No ATP Required, Along Concentration Gradient)

* Active (ATP Required, Against Concentration Gradient)

59
Q

Definition of Abiogenesis?

A

The formation of living cells from non-living materials (abiogenesis) is theorised to involve 4 four key processes

60
Q

What did biogenesis prove?

A

Cells only arise from pre-existing cells.

61
Q

What experiment replicated the conditions of a pre-biotic Earth in order to synthesize organic molecules? and the process.

A

The Miller-Urey experiment

Inorganic Compounds → Organic Compounds → Polymer→ Self Replication → Formation of cell.

62
Q

Who demonstrated the law of biogenesis?

A

Louis Pasteur

63
Q

How was the Louis Pasteur experiment done? (2)

A

• Broths were stored in sealed vessels that were sterilised
• Bacterial growth occurred if vessel was unsealed, but
did not occur if vessel stayed sealed (no contamination)

64
Q

What are the 6 stages of mitosis?

A
  • Interphase
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
  • Cytokinesis
65
Q

What happens in interphase of Mitosis? (3)

A

• DNA is uncondensed (chromatin)
• DNA is replicated (S phase) to form
genetically identical sister chromatids
• Cell grows in size and organelles are duplicated (G1 and G2)

66
Q

What happens in Prophase of mitosis? (3)

A
  • DNA supercoils and condenses (forms visible chromosomes)
  • Nuclear membrane dissolves
  • Centrosomes move to poles and begin to produce spindle fibres
67
Q

What happens in metaphase of mitosis? (3)

A
  • Centrosome spindle fibres attach to the centromere of each chromosome
  • Spindle fibres contract and move the chromosomes towards the cell centre
  • Chromosomes form a line along the equator (middle) of the cell
68
Q

What happens in anaphase of mitosis? (3)

A

• Spindlefibrescontinuetocontract
• Sister chromatids separate and move
to opposite sides of the cell
• Sister chromatids are now regarded as two separate chromosomes

69
Q

What happens in telophase of mitosis? (3)

A
  • Chromosomes decondense (DNA forms chromatin)
  • Nuclear membranes form around the two identical chromosome sets
  • Cytokinesis occurs concurrently
70
Q

What happens in cytokinesis of mitosis? (3)

A
  • Cytoplasmic division occurs to divide the cell into two daughter cells
  • Each daughter cell contains one copy of each identical sister chromatid
  • Daughter cells are genetically identical
71
Q

What is cancer?

A

Cancers are diseases caused by uncontrolled cell division • The resulting abnormal cell growths are called tumours

72
Q

What are the 2 was cancer can be developed?

A
  • Mutagens

* Genetics

73
Q

What is the process of cancer developing?

A

Normal cell → cancer cell → uncontrolled division → tumour.

74
Q

What are the 2 mechanisms cause the death of a cell?

A

•

•

75
Q

What are the 2 mechanisms cause the death of a cell?

A
  • Necrosis (uncontrolled ‘cell homicide’)

* Apoptosis (uncontrolled ‘cell suicide’)

76
Q

How to measure the mitotic index?

A

Mitotic Index = Cells in mitosis/Total number of cells

77
Q

What is the mitotic index?

A

The mitotic index is a measure of the proliferative status of a cell population (i.e. number of dividing cells)

78
Q

What is supercoiling?

A

During mitosis, chromatin condenses via supercoiling to become tightly packed chromosomes

BIOLOGY SL IBDP (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions