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Biology Unit 1 > Unit 1: Cell Biology > Flashcards

Unit 1: Cell Biology Flashcards

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1
Q

What does Cell Theory State?

A

That cells are the smallest possible unit of life and that living organisms are made up of cells.

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2
Q

What are the exceptions to Cell Theory?

A
  1. Striated skeletal → muscle fibres are not typical cells; they are multinucleate (have many nuclei per cell);
  2. Aseptate fungal hyphae → lack partitioning and have continuous cytoplasm
  3. Giant algae → Unicellular organisms that are very large in side (~7cm)
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3
Q

Define Magnification

A

The degree to which something is magnified

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4
Q

Define Resolution

A

The shortest distance between 2 points on a specimen

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5
Q

Define Unicellular (+ example)

A

An organism made up of 1 cell and that cell carries out all functions of life.
e.g Paramecium

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6
Q

Define Multicellular (+example)

A

An organism made up of multiple cells
(e.g human)

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7
Q

How do you work out magnification

A

I /A x M
I = Image Size
A = Actual Size
M = Magnification

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8
Q

What is the Surface Area to Volume Ratio?

A

The amount of surface area per unit of volume for an object.

When an object/cell is very small, it has a large surface area to volume ratio, while a large object/ cell has a small surface area to volume ratio.

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9
Q

Why is the S.A to Volume Ratio Important?

A

Explain this

S.A is important to determine the rate at which particles can enter/exit the cell. As a cell grows, volume (units3) increases faster than surface area (units2), leading to a decreased SA:Vol ratio

If metabolic rate exceeds the rate of exchange of vital materials and wastes (low SA:Vol ratio), the cell will eventually die
Hence growing cells tend to divide and remain small in order to maintain a high SA:Vol ratio suitable for survival

Volume is important to determine the rate at which the material is made or used up by the cell.

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10
Q

What are the Function of Life?

A

MRS GREN
Metabolism
Reproduction
Sensitivity

Growth
Reproduction
Excretion
Nutrition

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11
Q

Define ‘Metabolism’ as a function of life

A

All the enzyme catalysed reactions in a cell in order to maintain life.

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12
Q

Define ‘Homeostasis’ as a function of life

A

Living things maintain a stable internal environment

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13
Q

Define ‘Growth’ as a function of life

A

Living things can move and change shape or size

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14
Q

Define ‘Reproduction’ as a function of life

A

Living things produce offspring, either sexually or asexually

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15
Q

Define ‘Excretion’ as a function of life

A

the removal of toxic waste and wasteful products from the metabolism through the anus

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16
Q

Define ‘Nutrition’ as a function of life

A

the process of taking in nutrients, such as organic compounds and mineral ions containing energy for growth and tissue repair

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17
Q

What do Multicellular Organisms show?

A

Emergent Properties

a collection or complex system has, but which the individual members do not have.
i.e the heart, lungs

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18
Q

Define Differentiation

A

The normal process by which a less specialised cell develops or matures to possess a more distinct form and function.

Differentiation depends on gene expression which is regulated mostly during transcription.

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19
Q

Define Undifferentiated

A

Cells that have no specific job but has potential to become a different type of cell

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20
Q

Define Specialisation (+ example)

A

The structural adaption of a cell to suit a particular function

Eg: Red blood cells have no nucleus to make room for space to carry oxygen

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21
Q

What are Stem Cells ?

A

An undifferentiated cell that has not become specialised/adapted yet

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22
Q

What are the 2 key qualities of a Stem Cell

A
  1. Self Renewal - They can continuously divide and replicate
  2. Potency - They have the capacity to differentiate into specialised cell types
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23
Q

What is the ethical issue with using Stem Cells?

A

Since they are extracting this stem cell from pluripotent stem cells (embryos).

Harvesting these cells involves the death of an embryo and some people argue that it is taking a human life.

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24
Q

What is the general use of a stem cell?

A

Cell types that are not capable of self-renewal (e.g. amitotic nerve tissues) are considered to be non-stem cells
As these tissues cannot be regenerated or replaced, stem cells have become a viable therapeutic option when these tissues become damaged

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25
Q

What is the Therapeutic Use of Stem Cells?

A
  • Treat people who have certain types of cancer
  • Chemotherapy kills the cancer cells but also the normal cells in the bone marrow. This means that the patient cannot produce blood cells.
  1. Stem cells can be used to replace damaged or diseased cells with healthy, functioning ones
  2. The use of biochemical solutions triggers the differentiation of stem cells into the desired cell type
  3. Surgical implantation of cells into the patient’s own tissue
  4. Suppression of host immune system to prevent rejection of cells (if stem cells are from foreign source)
  5. Careful monitoring of new cells to ensure they do not become cancerous
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26
Q

What are the Types of Stem Cells and where to find them (4)

A

Decreasing in potency:

Totipotent: Can form any cell type, as well as extra-embryonic (placental) tissue (e.g zygote)

Pluripotent: Can form any cell type (e.g Embryonic Stem Cell)

Multipotent/somatic: Can differentiate into a number of closely related cell types (e.g adult stem cells) (found in the bone marrow)

Unipotent - Can not differentiate, but are capable of self renewal (e.g. progenitor cells, muscle stem cells)

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27
Q

Define potency

A

The ability of a stem cell to differentiate into different cell types.

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28
Q

Define Organelle

A

Anything inside a cell

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29
Q

What is a prokaryotic cell

A

Unicellular organisms that lack organelles or other internal membrane-bound structures.
They have a large chromosome
e.g bacteria

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30
Q

What are the features of a Prokaryotic Cell

A

The Cell Wall
The Plasma Membrane
Flagella
Pili
Ribosomes
The Nucleoid (region containing free DNA)

31
Q

What is the function of the Cell Wall

A

Protects the cell from the outside environment
Maintains the shape of the cell.
Prevents the cell from bursting if internal pressure rises.

32
Q

What is the function of the Plasma Membrane

A

Semi-permeable membrane that controls the substances moving into and out of the cell.
It contains integral and peripheral proteins. Substances pass through by either active or passive transport.

33
Q

What is the function of the Cytoplasm

A

Contains molecules such as enzymes which are responsible for breaking down waste and also aid in metabolic activity.

34
Q

What is the function of the Pili

A

Used for attachment and joining bacterials cells in preparation for the transfer of DNA from one cell to another (sexual reproduction)

35
Q

What is the function of the Vesicle

A

To store and transport molecules
(Vesicles form naturally during the processes of secretion (exocytosis), uptake (endocytosis) and transport of materials within the plasma membrane.)

36
Q

What is the function of the Flagella

A

Allows the cells to move

37
Q

What is the function of the Ribosomes

A

Site for protein synthesis

38
Q

What is the function of the nucleoid

A

Region containing naked DNA which stores the hereditary material (genetic information) that controls the cell and will be passed on to daughter cells.

39
Q

How do prokaryotic cells divide?

A

Binary fission.
A method of asexual reproduction involving the splitting of the parent organism into two separate organisms.

40
Q

What is a eukaryotic cell

A

Eukaryotes are organisms whose cells contain a nucleus (‘eu’ = good / true ; ‘karyon’ = nucleus)
They have a more complex structure and are believed to have evolved from prokaryotic cells (via endosymbiosis)

41
Q

What organelles are in the eukaryotic cell

A

Nucleus
Nucleolus
Nuclear Envelope
Nuclear Pore
Lysosome
Centrioles
Microtubules
Mitochondrion
Smooth Endoplasmic Reticulum
Rough Endoplasmic Reticulum
Plasma Membrane
Ribosomes
Golgi Body
Cytoplasm
Secretory Vesicle

41
Q

What is the function of the Rough Endoplasmic Reticulum (RER)

A

Has ribosomes on its exterior
Allows materials to travel around the cell
Made of ‘cisternae’
Proteins are transported from RER to Golgi Body

42
Q

What is the function of the Nucleus?

A

Contains genetic material of the cell (DNA)

43
Q

What is the function of the Smooth Endoplasmic Reticulum (SER)

A

Involved in the synthesis & transportation of lipids

44
Q

What is the function of the chloroplast?

A

Site of photosynthesis - manufactured organic molecules are stored in various plastids

45
Q

What is the function of Nucleolus?

A

Found in the nucleus & makes ribosomes

46
Q

What is the function of Lysosomes?

A

Membranous sacs filled with hydrolytic enzymes - Organelle that engulfs dead organelles

47
Q

What is the function of the Mitochondria?

A

Produces/stores energy [ATP] for the cell
Involved in aerobic respiration

48
Q

What is the function of the Golgi Apparatus?

A

Stores, modifies and packages proteins

49
Q

What is the function of the Microtubules?

A

Part of the cytoskeleton
Helps in the maintenance of the cell

50
Q

What is the function of the Vacuole?

A

Storage unit of Cell - has hydrolytic functions

51
Q

What is the function of the nuclear envelope?

A

Double Membrane envelope around the nucleus.

52
Q

Compare Prokaryotic and Eukaryotic Cells

A

DORA (mnemonic)
DNA (composition and structure)
Organelles (types present and relative sizes)
Reproduction (mode differs according to chromosome structure)
Average size (exceptions may exist)

Prokaryotic cells have naked DNA which is found in the cytoplasm in a region named the nucleoid.
On the other hand, eukaryotes have chromosomes that are made up of DNA and protein. These chromosomes are found in the nucleus enclosed in a nuclear envelope.

Prokaryotes do not have any mitochondria whereas eukaryotes do.

Prokaryotes have small ribosomes (70S) compared to eukaryotes which have large ribosomes (80S).

53
Q

What is Electron Microscopy?

A

Electron microscopes use electron beams focused by electromagnets to magnify and resolve microscopic specimens

54
Q

What are the 2 types of electron microscopes?

A

Light Microscopes use lenses to bend light

Electron Microscopes use electrons to focus electrons

55
Q
A
56
Q

Advantages of an electron microscope over light microscopes?

A

They have a much higher range of magnification (can detect smaller structures)
They have a much higher resolution (can provide clearer and more detailed images)

57
Q

Disadvantage of an electron microscope

A

they cannot display living specimens in natural colours

58
Q

What is the Structure of the Plasma Membrane [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

59
Q

How does the hydrophobic and hydrophilic properties of phospholipids help to maintain the structure of cell membranes?

A

Phospholipids act as a barrier to the substances

Forms Micelle

60
Q

What are the function of membrane proteins?

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
Anchorage - Attachment points for cytoskeleton and extracellular matrix
Transduction - Function as receptors for peptide hormones

61
Q

What is the function of cholesterol ?

A

Component in an animal cell protein that allows membrane to function at a wide range of temperatures
It is a type of lipid
Important in controlling membrane fluidity
More cholesterol = the less fluid, therefore less permeable the membrane

62
Q

What are integral proteins?

A

span across the bilayer
e.g carrier proteins/channel proteins
Transports substances through channel proteins : ions, sugars, amino acids

Other integral proteins are receptors for: hormones, neurotransmitters, enzymes

63
Q

What are peripheral proteins?

A

Confined in the inner or outer surface of the membrane

64
Q

Define Passive Transport

A

Does not require ATP
Only requires kinetic energy of particles

Types:
Diffusion
Facilitated Diffusion
Osmosis

65
Q

Define diffusion

A

Diffusion is the passive movement of particles from a region of high concentration to a region of low concentration.

66
Q

What are factors that affect diffusion

A

S.A
Temp
Size of Molecule
Stirring/Movement

67
Q

What is the formula for the Rate of Diffusion

A

(S.A x Difference in Conc) ÷ length of diffusion path

68
Q

Define Facilitated Diffusion

A

The passive movement of molecules across the cell membrane via the aid of a membrane protein.

69
Q

What are Channel Proteins

A

Forms pores in the membrane
Many only let one type of molecule through (small water soluble molecules/ions e.g Calcium Ions)

70
Q

Define Osmosis

A

The passive movement of water molecules, across a partially permeable membrane, from a region of lower solute concentration to a region of higher solute concentration.

71
Q

What are Carrier Proteins?

A

Molecules fit in at the membrane
Protein changes shape to pass molecules through

72
Q

Define Active Transport

A

Active transport uses energy to move molecules against a concentration gradient
involves the use of carrier proteins (called protein pumps due to their use of energy)

Biology Unit 1 (1 decks)

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