Cell Structure Flashcards
What does the nucleus do?
The nucleus contains the genetic material of the cell and controls the activities.
What is the nuclear envelope?
The nuclear envelope is the double membrane that surrounds the nucleus.
What does the nuclear envelope do?
It controls what goes in and out of the cell,
What are the nuclear pores?
They are holes that allow the passage of large molecules in/out of the nucleus
What is the nucleoplasm?
Granular, jelly like substance that makes up most of the nucleus
What is the nucleolus?
A small spherical region in the nucleus.
What is the function of the nucleolus?
Manufactures ribosomal RNA and assembles the ribosomes
What is the main function of the mitochondria?
Produce energy in the form of ATP
What is the structure of the mitochondria?
They have a double membrane structure.
What are cristae?
Extensions of the inner membrane
What do cristae provide?
They provide a large surface area for the attachment of enzymes and other proteins involved in respiration
What is the matrix?
A jelly substance in the mitochondria that contains proteins, lipids, ribosomes and DNA
What part of respiration takes place in the mitochondria?
The aerobic part (Krebs cycle and the oxidative phosphorylation pathway)
What is the function of chloroplasts?
To carry out photosynthesis
What is the chloroplast envelope?
double plasma membrane that surrounds the organelle
What does the chloroplast envelope do?
Controls what comes in and out of the organelle as it is highly selective
What are grana?
Stacks of up to 100 thylakoids
What are thylakoids
Disks that contain chlorophyll.
What takes place in the thylakoids?
The first stage of photosynthesis (light absorption)
What is the stroma?
Fluid filled matrix
What takes place in the stroma?
The second stage of photosynthesis (synthesis of sugars)
What do the granal membranes provide?
Large surface area for the attachment of chlorophyll, electron carriers and enzymes that carry out the first stage of photosynthesis.
What is in the stroma?
All the enzymes for the second stage of photosynthesis
Do chloroplasts have any other organelles?
They have ribosomes and their own DNA
What is the ER?
System composed of sheet like membranes.
What is the rough ER?
ER with attached ribosomes
What is the function of the rough ER?
Provide large surface area for the synthesis of proteins. Provide a pathway for the transport of materials throughout the cell
What is the function of the smooth ER?
To synthesise store and transport lipids. To synthesise store and transport carbohydrates.
What is the golgi body?
Stacks of membranes that make up flattened disks with small hollow rounded structures called vesicles.
What is the function of the golgi body?
To modify proteins, often adding non protein elements such as carbohydrates. Produce secretory enzymes. Secrete carbohydrates. Transport store and modify lipids. Form lysosomes.
What are lysosomes?
Vesicles containing enzymes such as proteases and lipases.
What is the function of the lysosomes?
Hydrolyse material ingested by phagocytic cells. Release enzymes outside of the cell. Digest worn out organelles. Completely break down cells after death (autolysis
Where are lysosomes especially abundant?
In secretory cells such as epithelial cells and in phagocytic cells.
What are ribosomes?
Small cytoplasmic granules
What is the function of ribosomes?
To synthesise proteins
What size of ribosomes are found in eukaryotic cells?
80S
What size of ribosomes are found in prokaryotic cells?
70S
What are ribosomes made of?
Two subunits
What are the subunits called?
Large and Small
What do the subunits contain?
Ribosomal RNA and proteins
What is a cell wall made from?
Microfibrils of the polysaccharide cellulose
What does the cell wall provide?
It holds the cells turgid, prevents them from bursting. Also allows water to pass along it.
What are the cell walls of fungi made from?
Chitin (another polysaccharide)
What is the middle lamella?
Thin layer that marks the boundary between adjacent cell walls and cements adjacent cells together.
What does the vacuole contain?
Mineral salts, sugars, amino acids, wastes and sometimes pigments.
Waht do vacuoles do to the cell?
Keep the cell turgid. The sugars and amino acids can act as a temporary store of food.
What do the pigments in the vacuole do for the plant?
Attract pollinating insects
