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Biology AS > Unit 1.2 > Flashcards

Unit 1.2 Flashcards

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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
Rough ER?
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
26
Smooth ER?
Comprises membranes that lack ribosomes. It is associated with the synthesis and transport of lipids
27
Ribosomes?
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
Golgi Body?
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
Lysosomes?
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
Centrioles?
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
Vacuoles?
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
Cell wall?
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
Plasmodesmata?
fine strands of cytoplasm that extend through pores in plant cell walls connecting the cytoplasm of one cell with that of another
34
Differences between animal cells and plant cells ?
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
Organelles are interrelated?
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
Prokaryote?
simple celled organism, lacking membrane - bound organelles such as a nucleus with its DNA free in the cytoplasm
37
Eukaryote?
An organism containing cells that have membrane bound organelles with DNA in chromosomes within the nucleus
38
Viruses?
not made of cells and are not classified with living organisms. seem to exist at interface between living and non living systems
39
Example of Prokaryotic cells ?
bacteria and Archaea
40
Distinguishing features of prokaryotes?
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
Differences between prokaryotes and eukaryotes?
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
Viruses?
not made of cells and so are described as acellular no organelles no chromosomes or cytoplasm
43
Diseases caused by viruses?
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
Differentiation?
the development of a cell into a specific type
45
Stem cells?
undifferentiated cell with the potential to become any cell type
46
Tissue?
A group of cells working together wit a common function structure and origin in the embryo
47
Epithelial tissue?
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
Simplest form?
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
Columnar epithelium?
have elongated cells Those lining tubes that substances more through such as oviduct and trachea have cilia
50
Squamous epithelium?
consists of flattened cells on a basement membrane form walls of the alveoli and line the bowmans capsule of nephron
51
Skeletal muscle?
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
Smooth muscle?
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
Cardiac muscle?
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
connective tissue?
connects supports or separates tissue and organs contains elastic and collagen fibres in an extracellular fluid or matrix
55
Organ?
group of tissues working in a structural unit, working together and performing a specific function
56
Examples of organs?
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
Organ systems?
group of organs working together with a particular role all systems of body work together, making an organism
58
Examples of organ systems?
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
magnfication?
the number of times an image is bigger than the object from which it dervived
60
resolution?
the smallest distance that can be distinguished as 2 separate points in a microscope
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Biology AS (12 decks)

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