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Biology AS > Unit 1.2 > Flashcards

Unit 1.2 Flashcards

1
Q

What are all cells made up of?

A

phospholipids and proteins

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2
Q

Biological membranes?

A

so thin their structure cannot be distinguished in their light microscope and their electron microscope appear as a single line

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3
Q

Eukaryotic cells?

A

contain membrane-bound organelles which are enclosed enzymes in the cytoplasm

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4
Q

What is the advantage?

A

potentially harmful chemicals such as enzymes are isolated and molecules with particular functions such as chlorophyll can be concentrated in one area.

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5
Q

Membranes?

A

provide a large surface area for the attachment of enzymes involved in metabolic processes and they provide a transport system inside the cell.

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6
Q

Standard unit of measurement?

A

m

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7
Q

Organelle?

A

a specialised structure with a specific function inside a cell

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8
Q

SI units for length

A
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9
Q

kilometre?

A

km
0.001 per m
10 ^3 m
measured ecosystems

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10
Q

metre?

A

m
1 per m
1 number of metres
used in larger organisms

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11
Q

milimetre?

A

mm
1000 per metre
10 to the power of -3 number of m
used in tissues

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12
Q

micrometre?

A

meumetres
1,000,000 number per metre
10 to the power of -6
used to measure cells and organisms

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13
Q

nanometer?

A

nm
1,000,0000,000 number per metre
10 to the power of -9
used to measure molecules

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14
Q

What does the Nucleus look like ?

A

most prominent feature in the cell
usually spherical and 10 - 20 nanometres in diameter
contains DNA which with protein comprises the chromosomes
Chromosomes direct protein synthesis because they are the site of transcription
DNA also provides a site for DNA replication

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15
Q

Components of nucleus?

A

bounded by 2 membranes called the nuclear envelope with pores which allow the passage of large molecules, such as mRNA and ribosomes out of the nucleus
Outer membrane is continuous with endoplasmic reticulum
Granular material in nucleus = nucleoplasm. Contains chromatin which is made of coils of DNA bound to protein
During cell division, chromatin condenses into chromosomes
Within the nucleus, one or more small spherical bodies each called a nucleolus
Sites of formation of rRNA - constituent of ribosomes

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16
Q

Mitochondria?

A

often cylindrical and 1-10 nanometres in length
compromise
2 membranes, separated by a narrow fluid-filled inter-membrane space. The inner membrane = is folded inwards to form a Cristae
An organic matrix, which is a solution containing many compounds including lipids and proteins
A small circle of DNA so mitochondrion can replicate many compounds, including lipids + proteins
A small circle of DNA , so a mitochondrion can replicate and code for some of its proteins and DNA
70 s ribosomes which allow protein syngthesis

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17
Q

Function of Mitochondria?

A

to produce ATP in aerobic respiration
Some of the reactions occur in the matrix and others on the inner membrane
Cristae provides a large surface area for the attachment of enzymes involved in respiration

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18
Q

Why fo they need a plentiful supply of ATP?

A

they are metabolically active cells such as muscle cells need a lot of ATP as they contain many mitochondria reflecting the high metabolic activity taking place

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19
Q

Why do mitochondria have a larger surface area cylindrical than being sphere?

A

being cylindrical reduces the diffusion distance between the edge and centre making aerobic respiration more efficient

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20
Q

Chloroplasts?

A

occur in the cells of photosynthesising tissue
in many plants, highest conc is in the palisade mesophyll cells, just below the upper surface of the cells

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21
Q

Structure of Chloroplast?

A

Each chloroplast is surrounded by 2 membranes - comprising of the nuclear envelope
Stroma - fluid-filled and contains some of the products of photosynthesis, including liquid droplets and starch grains which can take up to a large part of the stroma
they contain 70s ribosomes and circular DNA which enable them to make some of their own proteins and self-replicate

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22
Q

Within the stroma?

A

many closed, flattened sacs called thylakoids
A stack of thylakoids = a granum
Each granum comprises between 2 and 300 parallel sacs
Chlorophyll = found in the thyalokoids
arrangement produces a large surface area, efficient for trapping light energy

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23
Q

Endosymbiotic theory?

A

theory that describes the origin of chloroplasts and mitochondria
As far back as 1883, the division of chloroplasts was seen to closely to resemble that of free cyanobacteria
In the 1920s, the idea that mitochondria was once independent bacteria = also suggested

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24
Q

Endoplasmic reticulum?

A

an elaborate system of parallel double membranes forming flattened sacs with interconnected, fluid-filled spaces between them called cisternae
ER is connected to the nuclear envelope
System allows the transport of materials through the cells
There are 2 types of ER.

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25
Q

Rough ER?

A

has ribosomes on the outer surface and transports the proteins made there
RER = present in large amounts in cells that make a lot of protein, such as cells making amylase in the salivary glands

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26
Q

Smooth ER?

A

Comprises membranes that lack ribosomes. It is associated with the synthesis and transport of lipids

27
Q

Ribosomes?

A

smaller in prokaryotic than eukaryotic cells
PRO = 70s whereas
EU = 80s where they occur singly or attached to membranes on the RER
ribosomes = one large and one small subunit
important in protein synthesis

28
Q

Golgi Body?

A

resembles the structure of ER but is more compact
Vesicles containing polypeptides pinch off from RER and fuse with the stack of membranes which constitute the Golgi Body
Proteins = packaged and modified

29
Q

Lysosomes?

A

small temporary vacuoles surrounding a single membrane formed by being pinched off from the Golgi body
contain and isolate potentially harmful digestive enzymes from the remainder of the cell.
Enzymes in lysosomes can also digest material that has been taken into the cell

30
Q

Centrioles?

A

occur in all animal cells and most protoctistans but not in the cells of higher plants
Located just outside the nucleus
Centrioles = 2 rings of microtubules, making hollow cyclinders positioned at right angles to one another
Together, sometimes called centrosome
during cell division, centrioles organise the microtubules that make the spindle

31
Q

Vacuoles?

A

Most plant cells have a large permanent vacuole which consists of a fluid-filled sac bounded by a single membrane, the tonoplast
they contain cell sap, a solution which stores chemicals such as glucose, amino acids and minerals + may store vitamins and pigments as in oranges
major role in supporting soft plant tissues

32
Q

Cell wall?

A

largely consists of cellulose
held together in microfibrils which = aggregated into fibres
Functions
Transport - gaps between the cellulose fibres make the cell wall fully permeable to water and dissolved molecules + ions
Mechanical strength - the structure of cellulose microfibrils = very strong
Communication between cells - cells have pores called pits through which strands of cytoplasm pass

33
Q

Plasmodesmata?

A

fine strands of cytoplasm that extend through pores in plant cell walls connecting the cytoplasm of one cell with that of another

34
Q

Differences between animal cells and plant cells ?

A

Animal cells dont have a cell wall whereas plant cells do
Animal cells dont have chloroplasts but plant cells do
Animals cells dont have plasmodesmata but plant cells dp
Animal cells have a temporary vacuole whereas plant cells have a permanent one
centrioles are present whereas in plant cells they are absent from higher plant cells
Energy store is glycogen in animal cells whereas its starch in plant cells

35
Q

Organelles are interrelated?

A

functions within the cell are related
Nucleus contains chromosomes in which DNA encodes proteins
Nuclear pores in the nuclear envelope allow mRNA molecules, transcribed off the DNA to leave the nucleus and attach to the ribosomes in the cytoplasm or on the rough ER
ribosomes contain rRNA transcribed from DNA located at the nucleolus
Protein synthesis occurs on ribosomes, producing proteins in their primary structure
Polypeptides = made on the ribosomes are moved through the RER and are packaged into vesicles. The vesicles bud off the RER and carry the polypeptides to the golgi body where they are chemically modified and packaged
Golgi body produces vesicles containing newly synthesised proteins. May be lysosymes - containing digestive enzymes used within the cell. May be secretory vesicles which carry proteins to the cell membrane for exocytosis
Phospholipids and triglycerides move through the smooth endoplasmic reticulum to various destinations in the cell

36
Q

Prokaryote?

A

simple celled organism, lacking membrane - bound organelles such as a nucleus with its DNA free in the cytoplasm

37
Q

Eukaryote?

A

An organism containing cells that have membrane bound organelles with DNA in chromosomes within the nucleus

38
Q

Viruses?

A

not made of cells and are not classified with living organisms. seem to exist at interface between living and non living systems

39
Q

Example of Prokaryotic cells ?

A

bacteria and Archaea

40
Q

Distinguishing features of prokaryotes?

A

have no nucleus
internal membranes so unlike eukaryotic cells have no membrane bound organelles
DNA loose in cytoplasm
Peptidoglycan (murein cell wall)
70S ribosomes
Cytoplasm
Cell membrane

41
Q

Differences between prokaryotes and eukaryotes?

A

PRO
small ( 1- 10 nanometres)
no organelles
DNA = free in cytoplasm
no nuclear envelope
Plasmids may be present
Murein cell wall
No chloroplasts
No mitochondria
present meosomes
70 S ribosomes

Eukaryotes
Larger ( 10 -100 nanometres)
Membrane bound organelles
DNA = combined with protein in chromosomes
double membrane- nuclear envelope
no plasmids
cellulose cell wall
chloroplast
present mitochondria
absent mesosome
80s ribosome

42
Q

Viruses?

A

not made of cells and so are described as acellular
no organelles no chromosomes or cytoplasm

43
Q

Diseases caused by viruses?

A

Humans
flu, chicken pox, cold HIV, mumps, rubella, Ebola
Plants
tobacco mosaic virus, cauliflower mosaic virus
Birds
Avian flu
Other mammals
swine flu, cow pox feline leukaeima virus

44
Q

Differentiation?

A

the development of a cell into a specific type

45
Q

Stem cells?

A

undifferentiated cell with the potential to become any cell type

46
Q

Tissue?

A

A group of cells working together wit a common function structure and origin in the embryo

47
Q

Epithelial tissue?

A

forms a continuous layer, covering or lining the internal and external surfaces of the body
Epithelia have no blood vessels but may have nerve endings.
The cells sit on a basement membrane, made of collagen and protein and vary in shape and complexity. Often have a protective or secretory function

48
Q

Simplest form?

A

simple cuboidal epithelium, in which cells have a cube shape and the tissue is just one cell thick.
Occurs in proximal convoluted tubule of the kidney nephron and ducts of salivary glands.

49
Q

Columnar epithelium?

A

have elongated cells
Those lining tubes that substances more through such as oviduct and trachea have cilia

50
Q

Squamous epithelium?

A

consists of flattened cells on a basement membrane
form walls of the alveoli and line the bowmans capsule of nephron

51
Q

Skeletal muscle?

A

attached to bones and generates locomotion in mammals
has bands of long cells or fibres which give powerful contraction but muscle tires easily
Voluntary muscles so you can choose whether to contract them or not

52
Q

Smooth muscle?

A

has individual spindle shaped cells which contract rhythmically but contract less powerfully than skeletal muscle. They occur in the skin, in the walls
of blood vessels and in the digestive and respiratory tracts.
You cannot control these muscles so are involuntary
do not have stripes either and are called unstriped muscle

53
Q

Cardiac muscle?

A

only occur in the heart
structure and properties are somewhat between skeletal and smooth muscle
have stripes but lack long fibres of skeletal muscle
contract rhythmically without any stimulation from nerves and hormones although these can modify their contraction
cardiac muscle do not tire

54
Q

connective tissue?

A

connects supports or separates tissue and organs
contains elastic and collagen fibres in an extracellular fluid or matrix

55
Q

Organ?

A

group of tissues working in a structural unit, working together and performing a specific function

56
Q

Examples of organs?

A

e.g in the eye contains nervous, connective, muscle and epithelial tissues
in plants - leaf contains epidermal tissue, vascular tissue and ground tissue between vascular bundles

57
Q

Organ systems?

A

group of organs working together with a particular role
all systems of body work together, making an organism

58
Q

Examples of organ systems?

A

Digestive
Stomach and ileum
Excretory
Kidney and bladder
Skeletal
cranium and femur
Circulatory
heart and aorta
Reproductive
ovary and testis
Respiratory
trachea and lung
nervous
brain and spinal cord

59
Q

magnfication?

A

the number of times an image is bigger than the object from which it dervived

60
Q

resolution?

A

the smallest distance that can be distinguished as 2 separate points in a microscope

61
Q
A
61
Q
A
62
Q
A

Biology AS (12 decks)

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