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OCR BIOLOGY AS LEVEL > Basic Components of Living Systems > Flashcards

Basic Components of Living Systems Flashcards

Specification reference: 2.1.1

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1
Q

What is a microscope?

A

Instrument that enables you to magnify and object many times

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2
Q

Cell theory

A
  1. Plant and animal tissue is composed of cells
  2. Cells are the basic unit of all life
  3. Cells only develop from existing cells
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3
Q

Positives of light microscopes

A
  1. Easily available
  2. Cheap
  3. Portable
  4. Can be used to observe dead and living organisms
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4
Q

How many lenses do compound light microscopes have?

A
  1. Objective lens: Placed near the specimen

2. Eyepiece lens: Where the specimen is viewed

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5
Q

Objective Lens

A

Produces a magnified image which is magnified by the eyepiece lens. Configuration allow more magnification and less chromatic abberation

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6
Q

Magnification

A

How many times larger the image is than the actual size of the object being viewed.

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7
Q

Resolution

A

Ability to see individual objects as separate entities. Which then produces a detailed image.

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8
Q

Diffraction

A

Tendency for light waves to spread as they pass through samples.

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9
Q

How can resolution be increased?

A

By using beams of electrons which have a wavelength a thousand times shorter than light.

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10
Q

Magnification Equation

A

size of image / actual size of the image

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11
Q

Electron microscopy

A
  1. A beam of electrons with a wavelength of less than 1 nm is used to illuminate species.
  2. More detail of the ultra structure can be seen as electrons have smaller wavelength than light waves
  3. Magnification of x 500000 and will still have a clear resolution
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12
Q

What are the two types of electron microscopes?

A

Transmission electron microscopes

Scanning electron microscopes

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13
Q

Transmission Electron Microscope (TEM)

A

A beam of electrons is transmitted through a specimen and focused to produce an image. This has the best resolution with resolving power of 0.5 nm.

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14
Q

Scanning Electron Microscope (SEM)

A

A beam of electrons sent across the surface of the specimen and the reflected electrons are collected. The resolving power is from 3-10nm (not as good as TEM). Produces a 3D image.

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15
Q

Ultrastructure

A

Features that can be seen with an electron

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16
Q

Artifacts

A

Visible structure structural detail caused by processing the specimen and not a feature of a specimen

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17
Q

Laser scanning confocal

A

Moves a single spot of focused light across the specimen (point illumination). This causes fluorescence from the components labeled with a ‘dye’.

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18
Q

Conventional optical microscopes

A

Use visible light to illuminate specimens and a lens to produce a magnified image.

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19
Q

Fluorescent microscopes

A

Have a higher light intensity is used to illuminate a specimen that has been treated with a fluorescent dye.

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20
Q

Fluorescence

A

The absorption and re-radiation of light. Light of a longer wavelength and lower energy is emitted and used to produce a magnified image.

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21
Q

Cells

A

The basic unit of all living things

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22
Q

What are the two types of cell?

A

Prokaryotic and Eukaryotic

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23
Q

Prokaryotes

A

Are single-celled organisms with a simple structure of just a single undivided internal area called the cytoplasm (composed of cytosol which is made of water and organic molecules)

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24
Q

Eukaryotes

A

Made up of multicellular organisms (animals, plants, fungi). They have a more complicated structure containing a membrane-bound nucleus and cytoplasm which contains many membrane-bound cellular components.

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25
Q

Metabolism

A

Involves synthesis (building up) and the breaking down of molecules.

26
Q

Cytoplasm

A

Reactions take place in the cytoplasm. The cytoplasm separates the cell from its external environment by a cell-surface membrane. Cytoplasm provides distinct environments and conditions for different cellular reactions.

27
Q

Organelles

A

Membrane-bound components

28
Q

Membranes

A

Selectively permeable and control the movement of substances in and out of the cell and organelles. Membranes are fragile.

29
Q

Nucleus

A

Contains coded genetic material in the form of DNA molecules

30
Q

DNA

A

Directs the synthesis of all proteins required by the cell. DNA controls the metabolic activities

31
Q

Nuclear envelope

A

DNA contained in a double membrane to protect it from damage in the cytoplasm. It contains Nuclear pores which allow molecules to move in and out of the nucleus.

32
Q

Nucleolus

A

An area within the nucleus responsible for producing ribosomes. It is composed of protein and RNA. It is used to produce rRNA which is combined with proteins for photosynthesis

33
Q

Mitochondria

A

A site for the final stages of cellular respiration, where energy stored in the bonds of a complex organic molecule made available for the cell to use by the production of ATP,

34
Q

How many membranes do Mitochondria have

A

2.

35
Q

The inner membrane of the mitochondria

A

Folded to form structures called cristae and the fluid interior is called the matrix. The membrane forming the cristae contains enzymes used in aerobic respiration.

36
Q

Does Mitochondria have its own DNA?

A

Yes, it is called the mitochondrial (mt) DNA. Mitochondria can produce their own enzymes and reproduce themselves.

37
Q

Vesicles

A

Membrane sacs that have storage and transport roles. They consist simply of a single membrane with fluid inside. Vesicles are used to transport materials into the cell.

38
Q

Lysosomes

A

Are specialized forms of vesicles that contain hydrolytic enzymes. They are responsible for breaking down waste material in cells (including old organelles)

39
Q

Role of lysosomes

A

They have a role in the immune system as they are responsible for breaking down pathogens ingested by phagocytic cells. They play a role in apoptosis (cell death)

40
Q

Cytoskeleton

A

Present throughout the cytoplasm of all eukaryotic cells. It is a network of fibers necessary for the shape and stability of a cell. It controls cell movement + movement of organelles within cells.

41
Q

What are the three components of the cytoskeleton

A
  1. Microfilaments
  2. Microtubles
  3. Intermediate fibres
42
Q

Microfilaments

A

Contactile fibre formed from the protein actin. These are responsible for cell movement and cell contarction during cytokinesis

43
Q

Microtubules

A

Globular tubulin proteins polymerize to form tubes that are used to form scaffold-like structures that determine the shape of the cell. They act as tracks for movement of organelles including vesicles around the cell. Spindle fibers which have a role in the physical segregation of chromosomes in the cell division are composed of microtubules.

44
Q

Intermediate fibers

A

Provide mechanical strength to cells and make them maintain their integrity

45
Q

Centrioles

A

A component of the cytoskeleton present in most of the eukaryotic cells (exception of fungi and flowering plants). Composed of microtubules. Two associated centrioles form the centrosome, which is involved in the assembly and organization of the spindle fibers during cell division.

46
Q

Flagella

A

Are extentions that protrude from some cell types. Enable cells to have motility - in some cells.
In some cells they are used as a sensory organelle detcting chemical changes in the cell’s environment

47
Q

Cillia

A
  • Cillia can be mobile or stationary.
  • Each cilium contains two central microtubles (black circles) surrounding by the 9 pairs of microtubles arranged by a wheel (9+2 arrangement)
  • Pairs of the parallel microtubles slide over each other causing cilia to move in beating motion
48
Q

Stationary Cillia

A
  1. Stationary cilia are present on the surface of many cells and have important functions in sensory organs
49
Q

Mobile Cilia

A
  1. Mobile cilia beat in a rhythmic manner creating a current and cause fluids or objects adjacent to the cell to the move (trachea and fallopian tubes)
50
Q

What does DNA associate with…

A

Histones to form a complex called chromatin. Chromatin coils and condenses to form structures known as chromosomes (only visible when cells are being prepared to divide)

51
Q

Endoplasmic Reticulm

A

Network of membranes enclosed in flattened sacs called cisternae

52
Q

RER

A

Has ribosomes bound to the surface and is responsible for the synthesis and transport of proteins

53
Q

SER

A

Responsible for storage and lipid and carbohydrate production

54
Q

Golgi Apparatus

A

Compact structure formed of cisternae which doesn’t contain ribosomes.

55
Q

Role of the Golgi Apparatus

A

Modifies proteins and packages them into vesicles.

56
Q

Steps of protein synthesis: Step 1

A

Proteins are synthesised on the ribosomes bound to the endoplasmic reticulum

57
Q

Steps of protein synthesis: Step 2

A

They pass into the cisternae (ER) and are packaged as transport vesicles

58
Q

Steps of protein synthesis: Step 3

A

Vesicles containing newly synthesised proteins move towards the Golgi apparatus via the transport function of the cytoskeleton

59
Q

Steps of protein synthesis: Step 4

A

Vesicles fuse with the cis face of the Golgi apparatus and proteins enter. The proteins are structurally modifies before leaving the Golgi apparatus in vesicles from its trans face

60
Q

Steps of protein synthesis: Step 5

A

Secretory vesicles carry proteins that are released from the cell. Vesicles move towards + fuse with the cell-surface membrane releasing its contents via exocytosis. Some vesicles form lysosomes (which contain hydrolytic enzymes)

OCR BIOLOGY AS LEVEL (11 decks)

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