Chapter 1 - Cell Structure Flashcards
What is the nucleus surrounded with?
The nuclear envelope
Which part of the nucleus makes ribosomes?
The nucleolus
How can mRNA exit to the cytoplasm, and ATP enter to the nuclues?
Through the nuclear spores
What are the loosely coiled state of chromosomes called?
Chromatin
What are the function of genes? (2)
Controlling the activities of the cell and inheritance
Which form does the genetic code take when it’s about to undergo cell division?
The tightly coiled state - chromosomes
What is the endoplasmic reticulum made of?
Flattened compartments called ‘sacs’. They interconnect to form a complete system (reticulum)
With which organelle is the nuclear envelope continuous with?
The endoplasmic reticulum
Why is the rough endoplasmic reticulum dubbed as ‘rough’?
Because it has ribosomes attached to it
Where can ribosomes be found?
On the rough ER and the cytoplasm
What type of ribosomes do prokaryotes and eukaryotes have?
Prokaryotes have 70S while eukaryotes have 80S types
How large are ribosomes’ diameter?
25nm
What are ribosomes made of?
RNA (ribonucleic acid) and proteins
What are the sacs that break off from the ER called?
Vesicles
If vesicles join together, what organelle do they form?
Golgi body
What is the function of smooth endoplasmic reticulum
It makes lipids and steroids, and hormones (esp. reproductive ones)
How many golgi bodies can be found in an animal cell
between 10-20
What is the function of a golgi body?
To collect, process and sort molecules, to get them ready for transport either to the other parts of the cell or outside the cell
What is the process of transporting something outside the cell called?
Secretion
What are examples of processed molecules in the golgi apparatus? (3)
- making of glycoproteins
- removal of the first amino acid- methionine- from a sequence of proteins to make it functional
- in plants, enzymes in the golgi body converting sugars into cell wall components
How many membranes do lysosomes have?
one
How big is one lysosome?
0.1 - 0.5 micrometer in diameter
How many nanometers are in on micrometer?
1000
What types of enzymes do lysosomes have?
Hydrolytic (they use hydrolysis to break down molecules)
Why are the enzymes in lysosomes placed in sacs?
To prevent damage to the rest of the cell
What is the funciton of lysosomes?
They digest unwanted structures such as old organelles or whole cells
What are lysosomes used for in white blood cells?
Digestion of bacteria
Where are lysosomes found in sperm?
In the head of the sperm, in the form of acrosome
What is an example of enzymes being released to outside of the cell?
The replacement of cartilage in the bone
What is the advantages of light microscopes over electron microscopes?
- Easier to maintain
- Lower cost
- You can observe living things/ processes
- You can see the real life colours
- Or you can stain tissues to see their colours
- Easier to use
How big is a mitochondria’s diameter
1 micrometer
How many membranes does a mitochondria have? And what is the permeability type?
two. the inner membrane is semi-permeable, while the outer is fully permeable
What are the folds inside of the mitochondria called?
Cristae
What is the interior solution in the mitochondria called?
matrix
What is the name of the space between the membranes?
Intermembrane space
What is the transport protein in the outer membrane of the mitochondria called?
Porin
Which type of cells in the human body typically have more mitochondria than others?
Liver and muscle cells
What is the function of the mitochondria?
to carry out aerobic respiration and synthesise lipids
During respiration, a series of reaction take place in which energy is released from energy rich molecules such as?
Lipids (fats) and carbohydrates (sugars)
What molecule is energy transferred to in the mitochondria?
Adenosine triphosphate (ATP)
How does the inner structure of the mitochondria help it carry out its function?
There are enzymes in the matrix, which supply the hydrogen and electrons to the reactions that take place,
The foldings in the cristae help increase the surface area, thus increasing the efficiency of respiration
ATP is a small and soluble molecule, this is useful because…
it spreads rapidly to the parts of the cell where energy is needed
How is energy released from an ATP molecule?
By breaking it down to a molecule of adenosine diphosphate (ADP)
How this is the cell surface membrane?
7nm
How many layers does the cell surface membrane have?
three. called the ‘trilaminar appearance’
What are the finger-like extensions of the cell surface membrane called?
Microvilli
What is the function of microvilli?
Increasing the surface area of the surface membrane.
What is the meaning of a prokaryote?
An organism that lack a nucleus
What is a virus made out of?
A molecule made of RNA or DNA, surrounded by a protective coat of protein molecules
What is the name of the protein coat surrounding a virus?
capsid
What is a single protein molecule in the protein coat of a virus called?
capsomere
How long is one microtubule in diameter?
25nm
What is the cytoskeleton made up of?
microtubules, actin filaments, and intermediate filaments
Which structural component of cells determine the cell shape?
cytoskeleton
What protein is the microtubules made up of?
Tubulin. Alpha and beta tubulins which combine to form dimers
What do dimers make when formed end to end in a line?
protofilaments
How many protofilaments make up one microtubule
13
What are all the functions of microtubules? (5)
Support,
secretory vesicles and other organelles can be moved along the outside surface of the microtubules,
they hold membrane organelles in place,
during nuclear division, the spindle used for the separation of chromosomes are made of microtubules
They form part of the structure of centrioles
How many centrioles are in an animal cell and where are they located?
2, and they are found outside the nucleus, at right angles to one another
Which are region the centrioles found?
the centrosome
How long is a centriole
500nm
What is the centriole made of?
9 triplets of microtubules
What are MTOCs?
Microtubule organising centres
What are the centrioles at the bases of cilia and flagella called, and what are their role there?
They are called basal bodies, and microtubules extend from them into the cilia and flagella, which are responsible for their beating movements
What are the functions of the cell wall?
It gives the cell a defines shape, it prevents the cell from bursting when the water enters by osmosis
What is the permeability status of the cell wall?
freely permeable
What is the linkage between two cells’ cytoplasm called?
Plasmodesmata
What is the permanent vacuole in plants called?
the central vacuole
What is the membrane that covers the central vacuole called?
the tonoplast
What does the vacuole consist of? (6)
cell sap that contains; pigments, enzymes, sugars and other organic compounds like mineral salts, oxygen and carbon dioxide
What are the main functions of the vacuole?
regulating the osmotic properties of the cells, and keeps it turgid
What part of the chloroplast contains the chlorophyll?
thylakoids
How big is one chloroplast in diameter?
5-10 micrometers
How many membranes do chloroplast have? And what are their permeability status?
- The outer membrane is more permeable than the inner one.
Can chloroplast replicate by themselves?
Ye
What is the function of chloroplasts?
Carrying out photosynthesis
When thylakoids stack up, what are they called?
Grana
Why do chloroplasts sometimes change their orientation?
In order to receive the maximum amount of sunlight
What is the name of the fluid in the chloroplast?
Stroma
What are the lipid droplets in the stroma used for?
making membranes or from the breakdown of membranes in the chloroplast
How many coats does a typical prokaryote have?
Three; capsule, cell wall and cell membrane
What is the cell wall of a prokaryote made of?
a sugar called peptidoglycan (murein)
What are the small circle of DNA found in a prokaryotic cell?
Plasmid
What is the function of the pili?
Attachment to other cells or surfaces. It is also involved in sexual reproduction
How does the shape of chromosomes differ between prokaryotes and eukaryotes?
prokaryotic chromosomes are circular, while eukaryotic ones are linear
What is the cell wall of made of?
chitin
What is the definition of an organelle?
A functionally and structurally distinct part of a cell
What is compartmentalisation?
When organelles are often surrounded by membranes so that their activities can be separated from the surrounding cytoplasm
What does magnification mean?
the number of times larger an image is than the real size of the object
What does resolution mean?
the ability to distinguish between two separate points
Why can ribosomes be seen with an electron microscope but not with a light one?
because they are too small to interfere with light waves, but electron microscopes have a high frequency, therefore, ribosomes can interfere with them
How do you focus a light and electron microscope
optical lens, and electromagnets respectively.
Why can’t electron microscope have live specimens?
the electron beam must be in a vacuum, and specimens must be dehydrated because water boils in a vacuum
