Organelles Flashcards
(108 cards)
1
Q
What are the two different types of cells? what is the difference? what organisms fit into these cell groups?
A
prokaryotic and eukaryotic.eukaryotuc cells contain membrane bound organelles. Bacteria and archaea are prokaryotes. Animals, plants, fungi and protists are eukaryotes.
2
Q
what are the different classifications of organisms?
A
Bacteria, archaea, eukarya
3
Q
What are the kingdoms in taxonomy? how are the organisms within them similar?
A
Animalia, plantae, fungi and protista. They all contain membrane bound organelles.
4
Q
What is a prokaryotic cell?
A
relatively small and lack membrane bound organelles.
5
Q
what are eukaryotic cells?
A
relatively complex and large cells. They have membrane bound organelles.
6
Q
Do all organelles have membranes?
A
no
7
Q
What different membranes do eukaryotic cells have?
A
they have a plasma membrane surrounding the cytoplasm but also internal membranes that form compartments (organelles)
8
Q
What are enzymes?
A
proteins that act as catalysts and speed up reactions
9
Q
what are the roles of organelle membranes? (2)
A
The membranes control the movement of substances between the organelle and the cells cytosol and it allows the organelle to have a different composition to the cytosol and other organelles.
10
Q
What are the benefits of compartmentalisation? (3)
A
- allows enzymes and reactants for a particular reaction to be close together in high concentrations at the right conditions so that the organelles processes are efficient.
- allows processes that require different environments to occur at the same time, in the same cell
- makes the cell less vulnerable to changes in the environment, because changes will affect the cytosol more than the organelles.
11
Q
What are cells?
A
the building blocks of life. They transport oxygen, nutrients and waste, synthesis proteins and produce new life.
12
Q
How do different compartments communicate?
A
chemical messages (signals) help compartments communicate and ensure the cell is working well as a unit
13
Q
What is the structure and function of the nucleus? Visibility?
A
-double membrane bound and it contains DNA. It contains hereditary information. light microscope
14
Q
What is the structure and function of the rough endoplasmic reticulum? Visibility?
A
- It is membrane bound and is a system of cisternae. Ribosomes bind to its membrane.
- It processes and modifies proteins. electron microscope
15
Q
what is the structure and function of the ribosomes? Visibility?
A
- They are made up of proteins and rRNA.
- they synthesis proteins by translating mRNA into it. the mRNA specifies the sequence of amino acids. electron
16
Q
what are the structure and function of the Golgi Apparatus? Visibility?
A
- it is membrane bound and is made up of a stack of cisternae that are not connected to each other.
- It processes and packages proteins. electron
17
Q
what is the structure and function of the lysosome? Visibility?
A
- it is a membrane bound vesicle that contains digestive enzymes
- digests cellular waste material and foreign matter
electron
18
Q
what is the structure and function of the smooth endoplasmic reticulum? Visibility?
A
- it is membrane bound and a network of cisternae
- synthesises lipids
electron
19
Q
what is the structure and function of the mitochondria? Visibility?
A
- It has a double membrane. the inner membrane is highly folded. It also contains DNA
- it obtains energy from organic compounds
electron
20
Q
what is the structure and function of chloroplast? Visibility?
A
- a spherical or ellipsoidal with double membrane. It contains DNA and thylakoid sacs
- uses light energy, CO2 and eater to produce glucose.
light
21
Q
what is the structure and function of a centriole? Visibility?
A
- small structure in the cytoplasm, consisting of microtubules
- involved in cell division and the formation of cell structures such as flagella and cilia
electron
22
Q
what are the structures and functions of cilium and flagellum? Visibility?
A
- external structure consisting of microtubules
- involved in motility (the movement of substances across the surface of the cell
electron
23
Q
what is the structure and function of the vacuole? Visibility?
A
- a membrane bound, fluid filled vesicle
- stores substances and is involved in cell structure in plant cells.
light
24
Q
what is the structure and function of a plastid?
A
- small with a double membrane and contains DNA
- synthesises and storage of various organic molecules
25
What is the structure and function of a cell wall? Visibility?
- external structure surrounding the plasma membrane. Its composition depends on the type of cell.
- cell structure and protection. light
26
Do prokaryotic cells have any non-membrane-bound organelles?
yes but they are usually different in composition.
27
What organelles are not present in plants? (2)
lysosomes and sometimes centrioles.
28
what organelles are not present in animals? (2)
chloroplast and cell walls
29
Where is most of the DNA of a cell stored?
in the nucleus
30
How is the DNA in the nucleus organised? What is present in this DNA and what does this do?
in the form of linear chromosomes composed of DNA and protein. The information for synthesising proteins is present in the DNA and the genes in it are coped into messenger RNA which leaves and moves into the cytoplasm.
31
what is the most visible part of the nucleus? What is it made of? and what does it do? How can it be seen?
the nucleolus which is a non-dividing cell that is composed of proteins, DNA and RNA and it is where ribosomes are assembled.
32
How many ribosomes are there within cells and how big are they? How are they seen?
thousands and they are only 30nm in diameter so they can only be seen with an electron microscope.
33
What are ribosomes made up of?
two subunits that are joined together to form an 80S unit. One unit is 40S and the other is 60S
34
What places are ribosomes located? How does this change what they produce?
they are either free in the cytoplasm or bound to rough endoplasmic reticulum. Proteins produced by the free ribosomes function in the cytoplasm whilst proteins synthesised in the bound ribosomes are secreted out of the cell, packaged into organelles of inserted into the plasma membrane.
35
What is the ER and what are the differences between the two?
a network of intercellular membraneous sacs (cisternae) and tubles that link the plasma membrane with organelles. the Rough ER has ribosomes attached and the smooth ER does not.
36
What do the rough and smooth ERs do? where are they abundant?
RER- proteins from ribosomes pass through into its cavity and enzymes add sugar molecules to form glycoproteins. from there the proteins move to the Golgi body for export from the cell. abundant in cells that actively produce and export proteins eg. pancreatic cells that secrete digestive enzymes
SER- contains enzymes that produce molecules that aren't proteins such as phospholipids and steroids. abundant in cells that secrete steroids like cells in ovaries.
37
How are vesicles formed and what do they do in the Golgi apparatus?
they form in the cisternae and transport proteins from one to the next, modifying them for use by the cell or for transport out of the cell. Vesicles budding out also carry membrane bound proteins to plasma membrane and digestive enzymes to lysosomes.
38
What are the two faces of the Golgi apparatus? How are they different?
The cis face and the trans face. The cis face of the cisternae is connected to the ER directly or indirectly (by small transport vesicles). The trans face is connected to the plasma membrane by large secretory vesicles. The membranes of the faces are like the ER and plasma membrane in composition.
39
What substances does the Golgi apparatus package but not export from the cell?
some like enzymes found in lysosomes are not released.
40
what sort of cells have the largest and most developed Golgi bodies?
secretory cells
41
How are lysosomes formed?
when a transporting vesicle containing enzymes is released from the golgi and fuses with another vesicle called called an endosome which contains molecules brought into the cell by endocytosis.
42
What do lysosomes do?
they fuse with vesicles containing containing waste (eg. damaged organelles) or foreign matter and enzymes in the lysosomes break it down. Small re usable molecules are diffused back into the cytoplasm but the rest is retained by the lysosome or released from the cell by exocytosis
43
what is exocytosis?
the fusion of a vesicle with the cell membrane, expelling its contents outside the cell.
44
What is the process of the processing and synthesising of proteins and lipids?
- DNA is transcribed into RNA in the nucleus
- RNA leaves the nucleus and binds to ribosomes
- ribosomes synthesis proteins
- ribosomes on RER make proteins that are to be secreted out of the cell
- proteins are modified and packaged in the Golgi apparatus
- vesicles from the Golgi apparatus release contents from the cell by fusing to the cell membrane and also insert membrane bound proteins into the membrane
- SER processes and synthesises lipids
45
What are the two compartments of mitochondria?
The intermembrane space and the matrix. The matrix is a fluid filled space inclosed by the inner membrane and contains a double stranded DNA molecule. Different enzymes are found within each compartment and on each membrane.
46
what determines the number of mitochondria in a cell?
the energy requirements.
47
Why are chloroplasts green?
because their double stranded DNA molecules contain chlorophyll which is green pigment.
48
Where are chloroplasts present?
in plants and many protists but never animals or fungi.
49
What are the three membranes of chloroplasts?
outer, inner and the thylakoid system (disc shaped sac). These form compartments with different enzymes.
50
How does photosynthesis work in chloroplasts?
trap light energy which is used to split water into hydrogen and oxygen. The hydrogen then combines with CO2 to make glucose and oxygen is released.
51
How could chloroplasts and mitochondria once have been free living prokaryotes?
because they have their own DNA and double membranes.
52
What do vacuoles contain and what are the differences between plant and animal vacuoles? Are they in all cells?
they contain enzymes and organic and inorganic molecules. In animal cells they are small, temporary and numerous while plant cells have large, permanent ones that are surrounded by a membrane called tonoplast. It provides structural support by helping to maintain turgor and it seems lysosomes function here. They are in most cells.
53
What are plastids? What do they do? What are the different types? How do they form? Do all organisms have them? what are amyloplasts?
involved in synthesis and storage of chemical compounds. They contain double stranded DNA and have a double membrane. they develop from simple organelles called prop lasts. animals don't have them and they can be chloroplasts, leucoplasts (involved in storage) and chromoplasts (contain colour pigment and occur in petals and fruit). Amyloplasts are a type of leucoplast in plants that synthesises and stores starch but can convert it back to sugar when energy is required.
54
What is a cell wall? What cells have it? what is it made of?
a rigid structure outside the plasma membrane of plant cells, fungal cells and some prokaryotic cells. In plants it is mainly made up of cellulose, in fungi it is made up of chitin and in bacteria it is made of protein and murein.
55
What does the cell wall do?
It provides support and prevents expansion, allows water and dissolved substances through it.
56
What can give cell walls extra strength in woody plants?
lignin in the cell walls especially in the xylem (tissue in vascular plants that transports water and nutrients from roots)
57
What is the cytoskeleton made up of? What does it do?
consists of microtubules made of the protein tubulin and filaments of the protein actin. It supports the cells structure, allows it to move and assists with the transport of organelles and vesicles in cells.
58
What are centrioles made up of and what do they do? What cells have them?
A pair of small cylindrical structures comprised of microtubules. They are in most eukaryotic cells but not in plant cells. They are involved in cell division and formation of structures like cilia and flagella.
59
What are flagella and cilia? What are they made up of? What do they do? What is the difference?
hair like structures on the surface of cells that are made up of microtubules enclosed by an extension of the cell membrane. Cilia move with an oar like motion and are smaller and more numerous than flagella. Both help move the cells and things within in.
60
What are the main differences between plant and animal cells? (3)
- plants have a cell wall made of cellulose
- plants have a large permanent vacuole that stores minerals and nutrients in cell sap. They also provide support.
- plants have chloroplasts that preform photosynthesis
61
All cells must exchange nutrients and wastes with their environment. How do they do this?
via the plasma membrane.
62
What are bound to the plasma membrane?
enzymes
63
What affects the rate of exchange and can affect the processes catalysed by enzymes?
the surface area of the membrane
64
What are the main points of surface area ratio in relation to efficiency?
larger cells need to exchange more because of a lower surface area to ratio. Smaller cells have maximum efficiency.
65
What are the three ways of increasing the membrane surface area without changing the volume?
cell compartmentalisation, a flattened cell shape, plasma membrane extensions
66
How can cell compartmentalisation increase surface area to volume ratio?
This allows organelles to have the right conditions and concentration of enzymes and reactants for a function making processes highly efficient. It also allows eukaryotic cells to be larger than prokaryotic cells because it reduces the amount of exchange needed to maintain functions and creates more space for membrane bound enzymes , allowing increased activity
67
how can a flattened cell shape increase surface area to volume ratio? what is an example?
as the cel increases volume, the further away the cell membrane is away from the centre of the cell which means that the rate of exchange from the centre to the environment is too low to maintain the cell. To counteract, the cell gets flatter and reduces the distance substances must be transported. Red blood cells do this.
68
how can plasma membranes increase surface area to volume ratio? what is an example?
cells involved in absorbing nutrients or secreting wastes extend the SA of plasma membranes using finger like structures with hight SA called microvilli. eg. root hairs. Flattened shape wouldst help because they need high SA in some areas.
69
organs and organisms must also exchange substances with the environment how do they do this in a more efficient way?
BY increasing surface area with things like microvilli. In humans epithelial cells in the intestine are arranged into vili. This means that the 7m long intestine can still have 2000m squared room for absorption.
70
Where do cells live? What is this called?
cells exist in a watery environment of extracellular fluid which can be a large amount or just a thin surface layer.
71
How does the cell wall of plants affect the movement of molecules between the intra and extracellular fluids?
not much because it is pours.
72
Why does the composition of the extracellular fluid matter?
because it is where cells get the nutrients that they need.
73
What controls the movement of substances between the extracellular and intracellular fluid?
the plasma membrane
74
To unicellular organisms what is the extracellular fluid? How do they cope with change?
the environment in which they live that they have little control over and may die in if it changes. Some organisms like yeast are dormant until the environment returns to normal others slowly move to a better place.
75
To multicellular organisms what is extracellular fluid?
these more complex organisms have more control over it and are more independent of it. They have an outer layer that acts as a barrier and creates an internal environment that can differ to the external.
76
What can multicellular organisms change in their environment?
temperature, concentration of oxygen, concentration of CO2, pH, osmotic pressure (concentration of salt or ions), concentration of nitrogen wastes, concentration of glucose
77
What are some examples of extracellular fluid?
body fluid such as blood plasma or intestinal fluid
78
How is the plasma membrane made up? What does it do? What does its composition depend on?
it consists of two layers of phospholipid molecules with other molecules including proteins, carbohydrates and cholesterol scattered throughout. keeps the interior of the cell separate from the exterior. composition depends on the needs of the cell
79
Most membranes are asymmetrical. What does this mean?
The layers have different properties to each other eg. the pattern of proteins and carbohydrates.
80
What other functions does the plasma membrane preform?
functions such as cell recognition and commutation with other cells.
81
What are phospholipid bilayers like and why are they called bilayers?
they have a hydrophobic (water repelling) tail and a hydrophilic (water attracting) head. It is called a bilayer because it has two layers of phospholipids, the heads on the outer sides and the tails meeting in the middle.
82
What does the phospholipid nature of the plasma membrane mean for the cell?
the plasma membrane is impermeable to stare soluble particles, ions and polar molecules. The movement of these particles is controlled by protein channels which allows the exchange of molecules to be regulated. This is important for cellular respiration, digestion and elimination of wastes - to keep it alive.
83
Plasma membranes are fluid structures. what does this mean? What does the level of fluidity depend on?
that individual phospholipids and some proteins are free to move between the layers but they rarely go from one side to the other. depends on the percentage of unsaturated fatty acids in the phospholipid molecules. The higher the % the more fluid.
84
What is a phospholipid?
A molecule consists of long chain of fatty acids (hydrophobic) and a phosphate (hydrophilic). This is the major component of plasma membranes.
85
What is cholesterol and what does it do?
a fatty molecule that is between the phospholipids. cholesterol gives stability to the membrane without altering fluidity and reduces permeability of the membrane to small water soluble molecules.
86
where are proteins located in the membrane? What are the two different types? What do these two different types do?
They can move around but may be limited to certain areas. Proteins that are a permanent part of the membrane are called integral proteins. temporary ones are called peripheral proteins. When integral proteins span both layers they are called transmembrane proteins. Peripheral proteins bind to integral proteins or penetrate into the surface of the plasma membrane.
87
Where are carbohydrates in the membrane? what does this form? What do they do?
they are usually linked to protruding proteins (forming glycoproteins) or to lipids (glycolipids) on the outer surface of the membrane. They play the role of recognition and adhesion between cells and in the recognition of antibodies, hormones and viruses by cells.
88
What is the structure, function and visibility of the nucleolus?
- The most visible structure in the nucleus and a non-dividing cell that is composed of DNA, RNA and protein.
- where ribosomes are assembled
- light
89
What is the structure, function and visibility of the nuclear membrane?
- It contains pores and consists of a lipid bilayer
- pores link it with the cytoplasm and is a barrier allowing for compartmentalisation.
- light
90
What is cytoplasm?
fluid that fills the cell and organelles.
91
What is cytosol?
the jell-like fluid that id found in the cytoplasm and is made up of 80% water, nutrients, salts and organic molecules.
92
What do cytosol and cytoplasm do? visibility?
They support internal structures. They maintain the shape and consistency of the cell and contain chemicals and substances essential to life.
light
93
What is the structure, function and visibility of a chromosome?
- In the nucleus of a cell, the DNA molecule is packaged into thread like structures called chromosomes. made up of DNA that is tightly coiled many times around proteins called histones that support its structure.
- It passes down certain traits and instructions and allows DNA to be compact enough to fit into cells. It ensures that DNA is accurately replicated during cell division.
- light but only during cell division
94
What is the structure, function and visibility of a vesicle?
- A small structure within the cell, consisting of fluid enclosed by a lipid bilayer. Vacuoles, lysosomes, transport and secretory vesicles are all vesicles
- transport materials within the cytoplasm
- some can be seen light microscope
95
What is the structure and function of a microtubule?
- they are the largest cytoskeleton filaments. They have a tube shape and are a protein structure.
- They help cells maintain shape and assist in forming cell spindle during cell division.
96
What is the structure and function of a microfilament?
- a minute actin containing protein filament that is widely distributed through the cytoskeleton.
- plays a role in movement of the cell
97
what are similarities between microtubules and microfilaments?
they are both main components of supporting the cells cytoskeleton and are both seen with an electron microscope.
98
What has a cell membrane?
B
99
What has a nucleus?
e
100
Bacteria is an example of?
p
101
animals are an example of?
e
102
what contains membrane bound organelles?
e
103
what contains genetic material?
b
104
plants are an example of?
e
105
protists are an example of?
e
106
What has cytoplasm?
b
107
What has ribosomes?
e
108
fungi is an example of?
e
