Eukaryotic Cell Interiors Flashcards
What is the defining feature of eukaryotic cells?
The nucleus because prokaryotic cells do not have a nucleus.
About what percentage of the cell’s volume is made up by the nucleus?
About 6% of the total volume.
What is chromatin?
It is DNA wrapped in proteins called histones.
What is the function of chromatin?
Chromatin synthesizes messenger RNA.
How many chromosomes do humans have?
Humans have 46 chromosomes.
What is the nucleolus?
A specialized structure in the nucleus, consisting of chromosomal regions containing ribosomal RNA genesalong with ribosomal proteins imported from the cytoplasm.
What is the function of the nucleolus?
It is the site of ribosomal RNA synthesis and ribosome assembly.
What is the nuclear envelope?
A double phospholipid bilayer that surrounds the nucleus; the outer membrane is continuous with the endoplasmic reticulum.
What is the function of the nuclear envelope?
It has pores that regulate traffic with the cytoplasm and separates the nucleoplasm from the cytoplasm.
What is the nuclear lamina?
A net-like array of protein filaments that lines the inner surface of the nuclear envelope.
What is the function of the nuclear lamina?
It helps maintain the shape of the nucleus and holds the nuclear envelope to the chromatin.
What is the function of nuclear pores?
To import nucleotides and proteins, and to export mRNAs and ribosomes.
About how many pores are on a human nucleus?
Approximately 3000.
What are 80s ribosomes?
The 80s means that it is eukaryotic.
What are 70s ribosomes?
70s ribosomes belong to prokaryotic cells.
Where can 80s ribosomes be found?
In the endoplasmic reticulum and free in the cytoplasm.
How much of a cell’s membrane does the endoplasmic reticulum make up?
50-90% of the total membrane.
How much of the cell’s volume does the endoplasmic reticulum lumen make up?
About 15% of the cell’s volume.
What is the endoplasmic reticulum lumen?
The hollow space inside the endoplasmic reticulum.
What is the function of the rough endoplasmic reticulum?
It synthesizes export proteins, membrane proteins and membrane lipids.
What is the function of the smooth endoplasmic reticulum?
It acts as a place to put enzymes that are membrane proteins. Also involved in the synthesis of lipids.
Why would drug addicts have more smooth endoplasmic reticulum than non drug addicts?
Increased smooth ER allows the body to detoxify drugs better. Amount of ER changes based on need.
What are the components of the endomembrane system?
The plasma membrane, vesicles and vacuoles, nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, and peroxisomes.
Who discovered the Golgi apparatus?
Camillo Golgi.
What is the difference between Golgi apparatuses in plant and animal cells?
Animal cells have a single large stack of vacuoles, whereas plant cells have many small stacks of vacuoles.
What does the Golgi apparatus do?
It processes and sorts molecules made in the endoplasmic reticulum, as well as modifying and distributing proteins also made in the ER.
What are lysosomes?
They are vesicle-sized organelles filled with about 40 different hydrolysis enzymes.
What is the function of lysosomes?
They digest macromolecules.
What is the pH inside lysosomes and why?
The pH is about 5 because of the active import of H+.
What are peroxisomes?
They are vesicle-sized organelles filled with oxidative enzymes.
What is the function of peroxisomes?
They perform reactions that could damage other parts of the cell, such as fatty acid breakdown and hydrogen peroxide breakdown.
Name the three types of vacuoles.
Food, contractile, and central vacuoles.
What is the function of food vacuoles?
Used to store food during phagocytosis.
What types of cells have food vacuoles?
Amoebas and certain white blood cells.
What is the function of contractile vacuoles?
They are used by freshwater protists to expel water.
What is the function of central vacuoles?
They act like giant lysosomes inside plant cells.
What are proplastids?
They are small organelles with two membranes that mature into specific organelles that are required by the cell (found in plant and algae cells).
What are the three organelles that proplastids can mature into?
Storage plastids, chromoplasts, or chloroplasts.
What is the function of storage plastids?
They store fats, oils, or starches.
What is the function of chromoplasts?
They store pigments.
What is the function of chloroplasts?
They carry out photosynthesis.
What is the function of mitochondria?
To carry out cellular respiration.
Would structures such as flagella and microvilli appear on the same cell?
No, cells are specialized and would not have different structures that have the same function.
