Cell Structure Eu 2 Flashcards
How is the cytoplasm of a eukaryote divided?
The cytoplasm of eukaryotic cells is divided up into membrane-bound compartments called organelles.
What is the primary function of the plasma membrane in eukaryotic cells?
The plasma membrane surrounds all cells and controls the exchange of materials between the internal cell environment and the external environment.
What is the main structural component of the plasma membrane?
The fact that is it formed from a bilayer of phospholipids spanning a diameter of around 10nm.
What is the nucleus present it and what is it not?
The nucleus is present in all eukaryotic cells except for red blood cells.
What is the nucleus?
It is a large organelle that is separated from the cytoplasm by a double membrane (nuclear envelope) , which has many pores.
Why are nuclear probes important?
Because the nuclear pores provide important channels for allowing mRNA and ribosomes to travel out of the nucleus, as well as allowing enzymes and signalling molecules to travel in.
What does the nucleus contain?
The nucleus contains chromatin which is the material from which chromosomes are made.
What are chromosomes made of?
chromosomes are made of sections of linear DNA tightly would around proteins called histones.
Where is the rough endoplasmic reticulum found?
In plants and animal cells.
What is the surface of the rough endoplasmic reticulum covered in?
It is covered in 80S ribosomes.
How is the rough endoplasmic reticulum formed?
It is formed from folds of membrane continuous with the nuclear envelope. These flattened membrane sacs are called cistern.
What is the function of the rough endoplasmic reticulum?
-It processes the proteins made by the ribosomes.
What happens to the proteins synthesised by the ribosomes? How do they leave the cell?
The proteins synthesised by the ribosomes move to the cisternae, bud off into vesicles that carry the proteins to Golgi apparatus before being secreted out of the cell
What type of ribosomes are found in eukaryotes?
80S ribosomes
Where are the 80S ribosomes found in the cell?
They are found freely in the cytoplasm or as part of the rough endoplasmic reticulum in eukaryotic cells.
where are ribosomes constructed?
they are constructed in the nucleolus.
What is the function of ribosomes?
It is the site of translation, thus a part of protein synthesis.
What is the mitochondria the site of?
Mitochondria is the site of aerobic respiration within all eukaryotic cells.
With what are mitochondria visible?
Mitochondria are just visible with a light microscope.
What does the matrix produce?
The matrix contains enzymes needed for aerobic respiration, producing ATP.
What can also be found in the matrix?
Small, circular pieces of DNA (mitochondrial DNA) and ribosomes are also found in the matrix (needed for replication)
What does the Golgi apparatus consist of?
Flattened sacs of membrane called cisternae
What is the function of the Golgi apparatus?
Modifies proteins and lipids before packaging them into Golgi vesicles
What is the function of the Golgi vesicles?
The vesicles then transport the proteins and lipids to their required destination
What are the proteins that pass through the Golgi apparatus usually?
-Exported
-Put into lysosomes
-Delivered to membrane-bound organelles.
What are vesicles?
Vesicles are membrane bound sacs for transport and storage.
What are lysosomes?
Lysosomes are specialised vesicles that contain hydrolytic enzymes.
What do microtubules make up?
Microtubules make up the cytoskeleton of the cell and are about 25nm in diameter.
What is the cytoskeleton used for?
It is used to provide support and movement to the cell.
What are microfilaments?
They are part of the cytoskeleton made from actin proteins.
They assist with cell movement.
What are structures found in plant cells?
Chloroplasts
Permanent vacuole
Cell wall
What is the function of the cell wall? How?
It offers structural support to the cell as it is formed outside of the cell membrane.
The structural support is provided by the polysaccharide cellulose in plans, and peptidoglycan in most bacterial cells.
What is the large permanent vacuole?
A sac in plant cells surrounded by the tonoplast which is a selectively permeable membrane.
Can animal cells contain large permanent vacuoles?
yes but they are temporary and small.
What are chloroplasts the site of?
They are the site of photosynthesis.
By what is the chloroplast surrounded?
By a double membrane
How is grant in chloroplasts formed?
Membrane-bound compartments called thylakoids containing chlorophyll stack to form structures called grana
By what are grand joined together?
lamellae which are thin and flat thylakoid membranes.
Why does the chloroplast contain small circular pieces of DNA and ribosomes?
To synthesise proteins needed in chloroplast replication and photosynthesis
Where does the light-dependent stage of photosynthesis take place?
In thylakoids
Where does the light-independent stage of photosynthesis take place?
Stoma
What are the functions of life?
-metabolism
-reproduction
-response - sensitivity
-homeostasis
-growth
excretion
-nutrition
What is metabolism?
Metabolism - all the enzyme-catalysed reactions occurring in a cell, including cell respiration
What is reproduction?
Reproduction - the production of offspring. It may be sexual or asexual
What is homeostasis?
Homeostasis - the ability to maintain and regulate internal conditions within tolerable limits, including temperature
What is growth?
Growth - the permanent increase in size
What is response (sensitivity)?
Response - (or sensitivity), the ability to respond to external or internal changes (stimuli) in their environment. Thus improving their chance of survival
What is excretion?
Excretion - the disposal of metabolic waste products, including carbon dioxide from respiration
What is nutrition?
Nutrition - the acquisition of energy and nutrients for growth and development, either by, absorbing organic matter or by synthesising organic molecules (e.g. photosynthesis)
