Cells + Organelles Flashcards
What is an organism?
A living thing
What are some characteristics of a living thing?
reproductive capacity
growth
movement
metabolism
responsiveness
organised structure
death
Are viruses considered living?
Generally, no
What is a domain?
A level of classification above Kingdom
What are the three domains?
Archaea, bacteria and eukarya
Which two domains are the most similar?
Archaea and eukarya
What kingdoms are in Eukarya?
Plantae, animalia, fungi and protista
What is a prokaryote?
A celll lacking any membrane-bound organelles or a nucleus
What are all archaea and bacteria?
Prokaryotes
What is a eukaryote?
A cell with a membrane-bound nucleus and organelles
What is the size and complexity difference between eukaryotes and prokaryotes?
Eukaryotes are larger and more complex than prokaryotes
What are the three components of cell theory?
all organisms are made of one (unicellular) or more (multicellular) cells
new cells are formed by biogenesis (the division of pre-existing cells)
cells are the smallest organisational unit that a living thing can be
What is the difference between the plasma membrane of animal and archaea?
The archaea have uniquely structured membranes, able to maintain fluidity and permeability in extreme conditions. On the other hand, animalia membranes are selectively permeable but only in certain temperatures
Which cells have a cell wall?
all prokaryotes
fungi, plants and some protists
What are the cell walls of prokaryotes made of?
Murein: a mixture of proteins and carbohydrates
What are the cell walls of eukaryotes made of?
Mainly carbohydrates. Cellulose for plants. Chitin for fungi
Why have bacteria and archaea survived for so long?
Efficiency: Large SA:V ratio, so can replicate and metabolise quickly. All have a cell wall, offering extra protection. Can survive in a very diverse range of environments. Features that improve their resilience, such as flagella and pili
What are the features all cells have?
plasma membrane
cytoplasm
DNA (deoxyribose nucleic acid)
ribosomes
How many cells do prokaryotes have?
Unicellular
Do prokaryotes have chlorophyll sometimes?
Yes
What is the prokaryote’s form of genetic information storage?
A single circular DNA chromosome (nucleoid/nuclear region)
What genetic information storage do some prokaryotes have?
Plasmids: extra-chromosomal loops of double-stranded DNA
What are some add-ons that prokaryotes might have?
Pili, flagella, plasmids, polysaccharide capsule
What can prokaryotes be classified as: gram _ or _?
Postive or negative
What is gram negative?
When bacteria are stained with a ‘gram’ stain and don’t absorb it. AKA they have a second lipid membrane around their capsule
What are archaea?
Prokaryotes found in extreme conditions, such as high temperatures
What are the conditions that some archaea can survive in?
High temps
Low temps
Upper atosmophere
Very alkaline
No Light
Petroleum
Very acidic
Very salty
Little to no oxygen
Very arid
What are bacteria cell walls made of?
Peptidoglycan (murein)
What do many bacteria have surrounding them?
Cell capsule, for protection
What are pili?
Small hair-like projections
What do pili do in bacteria?
Can be used to transfer DNA between bacteria, assist movement and attach to surfaces
What are pili called if they attach to things?
Fimbriae
Do all bacteria have pili?
No, many do though
What are the three types of bacteria?
Photosynthetic:
use sun to make energy
Chemosynthetic: use energy made by chemical reactions
Heterotrophic: get energy through eating
Do all bacteria have flagella?
No, but many do.
What do bacteria use flagella for?
Movement/locomotion
What is different about archaea membranes?
They are adapted to withstand extreme conditions, so are a different structure
What are archaea cell walls made of?
A different type of peptidoglycan
Where do eukaryotic cells store their DNA?
In the nucleus, organised in linear chromosomes
What domain are protists?
Eukarya
Are protists diverse?
Very
How many cells do protists usually have?
One (unicellular) or they exist in cell colonies
What are protists mainly?
Heterotrophic, but some are also autotrophic (make food from raw materials and chemical reactions)
What does ‘motile’ mean?
Capable of motion
What allows protists to often be motile?
Cilia (in paracecium)
Flagella (in euglena)
Pseudopodia (in amoeba)
What domain is fungi?
Eukarya
What trophic are fungi?
Heterotrophic
How many cells do fungi have?
Multicellular, apart from yeast
What can fungi look like?
Plants, but they don’t have chlorophyll
What are fungi cell walls made of?
Chitin
Do fungi have cell walls?
Yes
What characterises fungi?
Masses of hyphae (filamentous growth used for vegetation growth)
Where do animal cells exist?
As a part of multicellular organisms with specialised cells of many types
Do animal cells have cell walls?
no
Are bacteria a domain or a kingdom?
Domain
What trophic are animalia?
heterotrophic
What is something that animalia can do?
Alter their shape for engulfment of foreign material
What is something that animalia sometimes have?
Flagella, allowing them to move
What is an example of animalia with a flagellum?
Spermatozoan
What is the cell wall of plants made out of?
Cellulose
In what way do plant cells exist?
As a part of multicellular organisms/plants with specialised cells of many different types
What are plants typically?
Autrotrophic, photosynthetic cells with chlorophyll
Example of fungi
mushrooms
example of protist
amoeba
what is the size of a prokaryotic cell
1-10um
What is the size of a plant cell?
30-50um
What is the size of an animal cell?
10-20um
Where are ribosomes in prokaryotes?
Scattered in cytoplasm
Where are ribosomes in eukaryotes?
Attached to rough endoplasmic reticulum or in cytoplasm
What does the plasma membrane do?
separate interior of the cell from the outside environment. controls what goes in and out. acts as boundary of cell
What is the cytoplasm?
Gel-like contents of the cell. Consists of cytosol (fluid component) and all organelles from the nuclear membrane to the plasma membrane
What occurs in the cytoplasm?
Many cellular activities
Where is the cytoplasm located?
Between the nuclear membrane and and plasma membrane
What is the purpose of the cytoplasm?
Suspend organelles and gives structure. Also increases surface area
What is dissolved in the cytosol?
Ions, salt, organic molecules, more than 80% water
What are ribosomes?
Organelles that make proteins
What is DNA?
genetic material that controls all activities in the cell. contains heridatory information
What do cells have in order to be efficient?
High SA:V ratio
How do organelles increase SA:V ratio
By having membranes
Why does having separate organelles help with?
Allowing different processes to occur at the same time with ideal conditions, increasing efficiency
What are the organelles shared by animal and plant cells?
Nucleus, cytoplasm, ribosomes, rough and smooth ER, golgi body, cell membrane, mitochondria, vacuole/vesicles, cytoskeleton
What do plant cells have that animal cells don’t?
Chloroplasts, cell walls and large vacuoles
Where do chemical reactions take place in the cell?
Cytosol
Which organelles have a double membrane?
Nucleus, mitochondia, chloroplasts
What is an effective way to transport matierals in and out of a cell?
Diffusion
What happens when cells become larger?
its sa:v ratio decreases. diffusion ceases to be an effectiven way to exchange materials with its environment
What is the controlling factor for cell size?
Effectiveness of diffusion
How do nutrients and wastes move across a cell surface?
Diffusion
What is the cell’s metabolism?
The chemical reactions that take place within a cell
What happens the SA:V ratio as the size of an object increase?
it decreases
What depends on the surface area?
The rate at whcih materials enter and leave the cell
What depends on volume?
The rate that materials are used or produced on the volume
Why is a high SA:V ratio important?
The surface area relates to how much material can enter a cell at one time. The volume relates to how much matieral is needed at one time, with the higher the volume, the more matieral needed to maintain it. A higher SA:V means more efficiency, improving the cell’s life. Larger cells have trouble exchanging materials at fast enough rates to sustain themselves
How did plants and animals overcome the restriction of cell size?
Becoming multicellular
How do animals and plants increase their effective surface area, considering they have a lower SA:V for their entire organism compared to other organisms?
Many adaptations
What are the ways to increase SA?
- Add compartments within the mebrane (organelles)
- Flatten the shape
- Add extensions of the plasma membrane (cilia)
- Add folds (e.g. cisternae in mitochondria)
What is an organelle?
A specialised structure or compartment within a cell with a specific function. THere are memrane-bound and non-membrane-bound organelles
What is compartmentalisation?
Separating the cells into different parts (organelles) to allow individual microclimates to be created thus each cell has the right conditions to perform effectively
Where is the plasma membrane located?
around the cell
What is the structure of the plasma membrane?
Porous, semi-fluid phospholipid bilayer
Where is the plant cell wall located?
Around the plasma membrane
What is a plant cell wall made of specifically?
Cellulose fibres with branched polysaccharides
Function of plant cell wall
Maintain cell shape and prevent excess uptake of water
What are the organelles involved in the synthesis and processing of lipids and proteins?
Nucleus, ribosomes, rough ER, smooth ER, lysosomes, golgi apparatus
What are the organelles invovled in energy transformations?
Mitochondria and chloroplasts
How do ribosomes make proteins?
They attach to each other, and follow the mRNA’s instructions of which amino acids to use. They then put together these amino acids to make a protein
Which organelles are involved in storage and cell structure?
Vacuole, plastids, cell wall, cytoskeleton, centrioles, cilia, flagella
What is the nucleus enclosed in?
Porous double membrane
Where is the nucleus?
In the cytoplasm
What is inside the nucleus?
chromatin
What is chromatin?
the genetic material of a cell
Function of nucleus
regulates all activites of cell
What do ribosomes do in the cytoplasm?
make cellular proteins
What do ribosomes do in rough ER?
make proteins for secretion
What are ribosomes make of?
Two ribosomal RNA subunits and protein. Not membrane bound
Function of ribosomes
synthesis of polypeptides (proteins)
Where is the rough endoplasmic reticulum?
Continuous in nuclear membrane and extends in cytoplasm
What is the strucutre of the rough ER?
complex structure of membranous tubules studded by ribosomes
Function of rough ER
transport of proteins
What do the membranes do in the rough ER?
Pinch off into sacs called vesicles to transport proteins
What is the nucleolus?
Part of the nucleus. A prominent strucutre
Where is the smooth ER?
Part of cytoplasm
What is the structure of the smooth ER?
system of membraneous tubules
What is the structure of the smooth ER?
system of membraneous tubules
Function of smooth ER
Synthesis of lipids, and transporting these lipids
What lipids does the smooth ER synthesise?
Oils, phospholipids, steroids, plasma membrane
What does synthesise mean?
Make chemical compounds by reacting simpler compounds
Where is the Golgi Body located?
cytoplasm
What is the structure of the Golgi Body?
A stack of flattened, unconnected membraneous sacs called cisternae
What does the Golgi body do?
Modifies, packages and stores proteins and lipids received from ER
What else does the Golgi Body do?
Exocytosis: transport of materials to the plasma membrane for export
Where are lysosomes usually found?
Cytoplasm of animal cells (sometimes other ones as well)
What is a lysosome?
Single membrane-bound sac containing lysozymes. Budd off Golgi Body
Function of lysosomes
intracellular digestion of old/damaged things. releases things into cell to cause apoptosis
What are mitochondria?
rod shaped organelles occuring in large numbers
What in the mitochondria is extensively folded?
the inner layer, forming cristae
Does mitochondria contain DNA?
some
What is the function of the mitochondria?
site of aerobic respiration
What is the membrane structure of a mitochondria?
Double.
Where are plastids located?
cytoplasm of plant cells and some protists
What are plastids?
Double membrane-bound organelles containing enzymes
What are three types of plastids?
Chloroplasts, chromoplasts, leucoplasts/amyloplasts
Function of chloroplasts
Site of photosynthesis
Function of chromoplasts
contain pigments that give colour to organism
Function of leucoplasts
storage of starch and fats
Where are chloroplasts located?
Cytoplasm of leaf and stem cells, some protists
What are chloroplasts?
Specialised plastids containing chlorophyll. Inside, there are stacks of flattened sacs (thylakoids) which are stacked together in grana
Do chloroplasts contain DNA?
some
What is a vacuole?
Membrane-bound, liqui filled sac
Function of vacuole
Provides turgour, stores water/inorganic molecules/sugars/amino acids
How are food vacuoles formed in animal cells?
Phagocytosis of food particles
What do contractile vacuoles in protists do?
Pump excess water from the cell
Is the cytoskeleton in prokaryotic cells?
No
Where is the cell’s cytoskeleton located?
The cytoplasm of eukaryotic cells
What is the cytoskeleton?
3D structure made of microtubules (hollow, cylindrical tubes) made of tubulin and microfilaments made of the protein actin
Purpose of cytoskeleton
Provide set of tracks for cell organelles to travel around, contract to change shape, provide structure
Where are the centrioles located?
Cytoplasm of animal cells, as a part of the cytoskeleton
What is a centrosome?
Two centrioles perpendicularly stacked
Function of centrioles
Involved in mitosis and organising spindle formation during cell division
What are some organelles unique to animal cells?
Lysosomes and centrioles (some in lower plant cells)
What are some organelles specific to plant cells?
Chloroplast, central vacuole, cell wall, starch granule (amyloplast)
What is each cilia or flagellum enclosed in?
Thin extension of a cell membrane, with fine protein filaments/microtubules
Do bacteria have flagellum?
Some do, protruding through the cell wall for movement
What are some features shared by plant and animal cells?
Nucleus, plasma membrane, ribosomes, mitochondria, golgi apparatus, ER, cytoskeleton, vesicles, vacuoles
Main function of plasma membrane
Control exchange of molecules between cytoplasm and external environment
What is the plasma membrane?
Phospholipid bilayer
What is the internal environment of a multicellular organism?
The extracellular fluid surround trhe cells
What factors are regulated in the internal environment of a cell?
Temperature, pH, osmotic pressure, concentration of glucose, O2, CO2
What is the permeability of the cell membrane?
Semi/partially/differentially/selective permeable
What is the model that describes the phospholipid bilayer?
Fluid mosaic model
What is the fluid mosaic model?
The membrane is made of a phospholipid bilayer embedded with proteins and other molecules. These substances can move laterally
What is a phospholipid containing?
Water soluble, hydrophilic, polar gylcerol head containing phosphate.
2 non-polar, insoluble, hydrophobic fatty acid tails
What are the traits of fatty acid tails in a phospholipid bilayer?
Non-polar, insoluble, hydrophobic
What are the traits of the head in a phospholipid bilayer?
Water soluble, hydrophilic, polar, glycerol-containing, phosphate
How do the phospholipids line up when in contact with an aqueous solution?
With the heads facing the outside and tails on the inside
What is an integral protein?
A protein embedded in the bilayer`
What is a peripheral protein?
A protein just on one side of the phospholipid bilayer
What is a transport protein?
An integral protein that allows proteins to pass through (carrier or channel)
What is a receptor protein?
An integral protein that binds to other receptors. Might instruct cell to change behaviour
What is a recognition protein?
A peripheral protein that attachs to glycoproteins that act as markers (antigens)
What is an adhesion protein?
A peripheral protein that links cells together
What are carbohydrate chains?
Linked to proteins (making glycoproteins) or lipids (making glycolipids). Involved in cell recognition and adhesion, and the recognition of antibodies/hormones/viruses
Where are carbohydrate chains found?
On one side of cell, looks like branch
Where are cholestrol molecules found?
Embedded in phospholipid bilayer, look like pills
What are cholestrol molecules?
Molecules that provide stability and reduce permeability of water soluble molecules
What is a transmembrane protein?
A protein that goes from one side to another in the phospholipid bilayer
Two examples of passive transport
Diffusion, facilitated diffusion, osmosis
Two examples of active transport
ion pumps, endocytosis
What is diffusion?
The movement of molecules from an area of high concentration to an area of low concentration (down a concentration gradient)
Factors affecting diffusion
Concentration (greater the difference, faster diffusion)
Temperature (higher = faster)
Particle size (smaller = faster)
Can water pass through the bilayer?
Yes, it can pass directly through because of its small size
What is cell lysis?
The bursting of a cell due to osmosis
What is haemolysis?
Cell lysis in blood cells
What does a cell wall do to prevent lysis?
Stops the influx of water
What is the role of a cell wall in preventing lysis?
Provides rigidity and wall pressure to counteract the influx of water
What happens if a plant cell is hypotonic to its environment?
It becomes flaccid (soft) and the vacuole collapses
What is crenation?
When an animal cell loses water to its environment
What is plasmolysis?
When the vacuole becomes so flaccid that it shrinks away from the cell wall. Full plasmolysis is irreversible
What does the term turgid refer to?
When a cell is swollen due to osmosis
What can diffuse easily through the bilayer?
Water, oxygen, CO2, lipid soluble+ non-polar + uncharged molecules
Which types of molecules cannot pass through the lipid bilayer without proteins?
Ions (charged), large polar molecules
What is the permeability of a large polar molecule?
Not permeable
What is an example of a large, polar molecule?
Amino acid, glucose
Facilitated diffusion
Passive transport down a concentration graident, aided by a protein channel that increase sthe permeability of cellular membranes to ions/water/soluble/large molecules. No energy neeed
What does a channel protein do?
Form narrow pathways (usually hydrophilic pores that small ions can diffuse through rapidly). only ions of a specific size and shape can pass through. they can open and close
What does a carrier protein do?
Molecules bind to a specific carrier protein. This changes their shape and allowes the molecule to pass through. Once complete, OG shape is restored. In passive transport, no energy is needed. In active transport, ATP binds to a receptor on the protein. Then, it breaks off one of the bases, releasing the energy needed to trigger carrier protein to work
What is the term for animal cells shrinking due to water loss?
Crenation
What type of molecule is oxygen?
SMall, uncharged
What is the permeability of small, uncharged molecules?
Permeable
Example of small, uncharged molecule
Carbon dioxide
What type of molecule is alcohol?
Lipid-soluble, non-polar molecule
What is the permeability of lipid-soluble, non-polar molecules?
Permeable
Examples of lipid-soluble, non-polar molecules
Alcohol, steroids, chloroform
What type of molecule is water?
Small polar molecule
Examples of small polar molecules
water and urea
What is the permeability of a small polar molecule?
Permeable or semi-permeable
What are examples of a small ions?
Potassium ion, sodium ion, chloride ion
What is the permeability of small ions?
Non-permeable
What type of molecule is an amino acid and glucose?
Large, polar, water-soluble molecule
What is the permeability of large, polar, water-soluble molecules?
Non-permeable
What direction is active transport?
From low concentration to high concentration
What is active transport?
movement of molecules from a low conc to a high conc. requires ATP/energy.
What is used in active transport?
Carrier proteins, sometimes called pumps
How are carrier proteins activated in active transport?
ATP attaches to a receptor. When it breaks into ADP and a base, energy is released. This triggers the carrier protein to change shape, releasing the molecule on the other side of the membrane
When is bulk transport used?
Moving large quantities of cells that are too big to fit through the carrier proteins
What are the two types of bulk transport?
Endocytosis and exocytosis
What is endocytosis?
the incorporation of substances from outside the cell into the cell, using a membrane-bound vesicle
What is phagocytosis?
Endocytosis of solids
What is pinocytosis?
Endocytosis of lipids
What is the purpose of exocytosis?
Releases substances from the inside of the cell to the outside
How does exocytosis occur?
The fusion of a vesicle membrane with the plasma membrane, releasing the contents to the outside of the cell
What are the steps of endocystosis?
- Matierals are brought to the plasma membrane. Then, invagination of the plasma membrane engulfs these materials
- Vesicles bud off the plasma membrane
- The vesicles are carried into the cell
What are the steps of exocytosis?
Vesicle carrying contents moves to the plasma membrane. Vesicle fuses with the plasma membrane, releasing the contents to the outside of the cell
