IAL Edexcel Biology > Unit 2: Cell structure & Organisation > Flashcards

Unit 2: Cell structure & Organisation Flashcards

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1
Q

who was the first person to view cells?

A

Robert Hooke

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2
Q

what idea did Schneider and Schwann come up with?

A

cell theory

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3
Q

define cell theory

A

all living organisms are made with cells. the cell theory is a unifying concept meaning that it is universally accepted.

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4
Q

what are the three main ideas included in cell theory?

A
  • all living organisms are made up of one or more cells
  • cells are the basic functional unit in living organisms
  • new cells are produced from pre-existing cells
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5
Q

what common features do cells of all living organisms share?

A
  • Cell surface membrane
  • Cytoplasm
  • DNA
  • Ribosomes
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6
Q

outline the differences between prokaryotic cells and eukaryotic cells

A

prokaryotic cells have no internal membranes and smaller ribosomes. while eukaryotic cells have several internal membrane-bound rganelles and larger ribosomes

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7
Q

what is a cell ultrastructure?

A

the internal structures of the cell

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8
Q

what are some examples of cells that are specialised for a specific function?

A
  • Epithelial cells in the small intestine are specialised to absorb food efficiently
  • Red blood cells are specialised to transport oxygen
  • Xylem cells in plants are specialised to allow the transport of water around a plant
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9
Q

define tissue

A

a group of cells working together o perform a specific function

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10
Q

what are examples of tissues?

A
  • Epithelial cells group together to form epithelial tissue the function of which, in the small intestine, is to absorb food
  • Muscle cells group together to form muscle tissue, the function of which is to contract in order to move parts of the body
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11
Q

define organ

A

an organ is a group of tissues working together to perform a specific function

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12
Q

what are examples of an organ?

A

— Many different tissues, including cardiac muscle tissue, blood vessel tissues and connective tissue, group together to form the heart, enabling it to function to pump blood around the body
— Tissues including palisade mesophyll, spongy mesophyll, and vascular tissue, group together in plants to form leaves, enabling them to perform photosynthesis effectively

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13
Q

define organ system

A

a group of organs working together to perform a specific function

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14
Q

define organelles

A

a component within a cell that carries out a specific function

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15
Q

define cells

A

basic functional and a structural unit in a living organism

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16
Q

what tissues is the stomach made up of?

A

made up of epithelial tissue, muscular tissue and glandular tissue

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17
Q

what tissues is the bladder made up of?

A

muscle tissue, epithelial tissue, connective tissue, and fatty tissue

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18
Q

what tissue is the eye made up of?

A

many that include: the retina, the cornea, sclera and choroid

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19
Q

what is the cell range in diameter of eukaryotic cells?

A

around 10-100 um, making them larger in size than prokaryotic cells

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20
Q

what is the cell range of prokaryotic cells in diameter?

A

0.1-5 um

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21
Q

what key structures do animal and plant cells share?

A

they both have eukaryotic cells that share key structures such as
- membrane-bound organelles, including a nucleus
- larger ribosomes known as 80s ribosomes

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22
Q

what are some key differences between animal and plant cells?

A
  • animal cells contain centrioles and some have microvilli while plant cells do not
  • plant cells have a cellulose cell wall, large permanent vacuoles, and chloroplasts while animal cells do not
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23
Q

what is a microvilli?

A

microvilli are folded regions of the cell surface membrane that increase cell surface area for absorption, e.g. in the small intestine

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24
Q

what is the function of the cell surface membrane?

A

all cells are surrounded by a cell surface membrane which controls the exchange of materials between the internal cell environment and the external environment

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25
why is the membrane described as being partially permeable?
some substances can pass through the membrane while others cannot
26
what is the diameter of the phospholipid bilayer of the cell membrane?
10 nm
27
define phospholipid and state their function
triglyceride in which one of the three fatty acid molecules is replaced by a phosphate molecule. phospholipids are important in the structure and functioning of plasma membranes.
28
what other name can the cell surface membrane e referred to as?
plasma membrane
29
where is the nucleus present?
in all eukaryotic cells
30
describe the structure of a nucleus
the nucleus is relatively large and separated from the cytoplasm by a double membrane called nuclear envelope which has many pores
31
what are nuclear pores?
Nuclear pores are important channels for allowing mRNA and ribosomes to travel out of the nucleus, as well as allowing enzymes, e.g. DNA polymerases, and signalling molecules to travel in
32
chromatin
the nucleus contain chromatin, the material from which chromosomes are made
33
what are chromosomes made off of?
chromosomes are made of sections of linear DNA tightly wound around proteins called histones
34
what are the darkly stained regions of the nucleus that can be observed under a microscope?
these regions are individually termed nucleolus (plural nucleoli) and are the sites of ribosome production
35
what is the function of the mitochondria?
it is the site of aerobic respiration within eukaryotic cells
36
when are the mitochondria visible?
just visible with a light microscope
37
define respiration
the chemical process by which energy is released from glucose to produce ATP inside living cells. aerobic respiration requires oxygen, while anaerobic respiration does not.
38
describe the structure of the mitochondria
- Mitochondria are surrounded by a double-membrane with the inner membrane folded to form structures called cristae - The matrix of mitochondria contains enzymes needed for aerobic respiration, producing ATP - Small circular pieces of DNA, known as mitochondrial DNA, and ribosomes are also found in the matrix
39
what is the function of mitochondrial DNA and ribosomes found in the matrix?
these are needed for replication of mitochondria before cell division
40
where can ribosomes be found?
Ribosomes can be found as free organelles in the cytoplasm of all cells or as part of the rough endoplasmic reticulum in eukaryotic cells. - they are not surrounded by a membrane
41
each ribosome is a…
complex of ribosomal RNA (rRNA) and proteins
42
where are 80s and 70s ribosomes found?
- 80s ribosomes are found in eukaryotic cells - 70s ribosomes are found in prokaryotes, mitochondria and chloroplasts
43
ribosomes are the site of…
translation
44
what are the two types of endoplasmic reticulum?
- Rough Endoplasmic Reticulum (RER) - Smooth Endoplasmic Reticulum (SER)
45
how is the Rough Endoplasmic Reticulum (RER) formed?
- RER is formed from folds of membrane continuous with the nuclear envelope - the surface of RER is covered in ribosomes
46
what is the role of the RER?
to process proteins made on the ribosomes
47
how is the Smooth Endoplasmic Reticulum (SER) formed?
- SER is also formed from folds of membrane but its function is distinct from the RER - SER does not have ribosomes on its surface
48
what is the function of SER?
being involved in the production, processing and storage of lipids, carbohydrates and steroids
49
describe the structure of the Golgi Apparatus?
it consists of flattened sacs of membrane (similar in appearance to the smooth endoplasmic reticulum)
50
what can the golgi apparatus sometimes be known as?
as the golgi body
51
how can the Golgi be distinguished from the SER?
by its regular, stacked appearance; it can be described as looking like a wifi symbol!
52
what is the role of the Golgi apparatus?
to modify proteins and lipids before packaging them into Golgi vesicles. The vesicles then transport the proteins and lipids to their required destination
53
Proteins that go through the Golgi apparatus can be:
- Exported from the cell, e.g. hormones such as insulin - Put into lysosomes, e.g. hydrolytic enzymes - Delivered to other membrane-bound organelles
54
what are Lysosomes?
Lysosomes are specialist forms of vesicle which contain hydrolytic enzymes
55
what is the role of lysosomes?
to break down waste materials such as worn-out organelles, Lysosomes are used extensively by cells of the immune system and in programmed cell death, known as apoptosis
56
what are centrioles made up of?
hollow fibres known as microtubules
57
what are microtubules?
Microtubules are filaments of protein that can be used to move substances around inside a cell, as well as to support the shape of a cell from the inside
58
how are centrosomes formed? and what is their function?
two centrioles at right angles of each other form a centrosome which organises the spindle fibres during cell division
59
what is the function of spindle fibres?
spindle fibres form the spindle apparatus which are responsible for pulling the chromatids to separate ends of the cell.
60
are centrioles found in plants and fungi?
No, centrioles are not found in plants and fungi
61
what organelles are involved in protein synthesis?
— Nucleus Transcription of the DNA code occurs here — Ribosomes Free ribosomes and those on the RER produce proteins in the process of translation — Rough endoplasmic reticulum (RER) — Golgi apparatus — Cell surface membrane > Proteins formed within the cell are secreted here
62
63
the formation of extracellular enzymes includes:
1- the nucleolus manufactures ribosomes for protein synthesis in the RER 2- the nucleus manufactures mRNA, which is needed by ribosomes to make proteins 3- the ribosomes in the RER make proteins 4- the RER processes the proteins which are then sent in vesicles to the golgi body 5- the golgi body further processes the proteins and sends them in vesicles to the plasma membrane 6- the vesicles fuse with the plasma membrane to secrete the finished protein project
64
how do prokaryotic cells differ from eukaryotic cells?
— prokaryotic cells are much smaller than eukaryotic cells — they also differ in having: > a cytoplasm that lacks membrane-bound organelles > they have 70s ribosomes > no nucleus > a cell wall
65
what do prokaryotic cells have instead of a nucleus?
a single circular bacterial chromosome that is free in the cytoplasm and is not associated with proteins
66
what does a prokaryotic cell wall contain?
glycoprotein murein
67
what is murein sometimes known as?
peptidoglycan
68
describe the structure of prokaryotic cells
> they’ve loops of DNA known as plasmids > capsules > flagella > pili > a cell membrane that contains folds known as mesosomes
69
describe the structure and function of the flagellum
A long, hair-like structure that rotates, enabling the prokaryote to move. some prokaryotes have more than one. *not present in all prokaryotes
70
what is the structure and function of the pili?
it has a thread-like structures on the surface of some bacteria. its function is for attachment to other cells or surfaces: involved in sexual reproduction
71
what is te structure of the plasmids?
small loops of DNA that are separate from the main circular DNA molecule. plasmids contain genes that can be passed between prokaryotes (e.g. genes for antibiotic resistance). * not present in all prokaryotes
72
what is the structure and function of a prokaryote capsule?
a capsule is the final outer layer of *some prokaryote cells. this is sometimes called the slime capsule. the function of a capsule is to protect bacteria from drying out and from attack by cells of the immune system of the host organism.
73
describe the structure and function of mesosomes
folded regions in the plasma membrane of some prokaryotic cells. they have many functions including aerobic respiration, cell wall formation and DNA replication.
74
describe the structure and function of circular DNA
the genetic material of prokaryotic cells mainly consists of a single circular strand of DNA that is not contained in a membrane -bound nucleus. the area in the prokaryotic cells mainly consists where this circular DNA molecule is found is known as the nucleoid.
75
what is the function of 70s ribosomes in a prokaryotic cell?
they are the site of protein synthesis in prokaryotic cells
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