Cell Structure (College Board AP® Biology): Flashcards
0Still learning
Know0
Define ribosome.
Was this flashcard helpful?
Cards in this collection (40)
Define ribosome.
A ribosome is the site of protein synthesis; it is a non-membrane structure composed of protein and ribosomal RNA (rRNA).
True or False?
Ribosomes are found in all cells, both prokaryotic and eukaryotic.
True.
Because ribosomes are present in all forms of life, they support the view that all living things share common ancestry.
What is the difference between free and bound ribosomes?
Free ribosomes are suspended in the cytoplasm (found in all cells)
Bound ribosomes are attached to the endoplasmic reticulum to form rough ER (only in eukaryotic cells)
Define endomembrane system.
The endomembrane system is a group of membrane-bound organelles and subcellular components that work together to modify, package, and transport polysaccharides, lipids, and proteins within the cell.
The surface of the rough endoplasmic reticulum is studded with , which help carry out protein synthesis.
The surface of the rough endoplasmic reticulum is studded with ribosomes, which help carry out protein synthesis.
What are the two main functions of the smooth endoplasmic reticulum (SER)?
Detoxification of cells
Lipid synthesis
Define Golgi complex.
The Golgi complex is a membrane-bound structure made of a series of flattened membrane sacs (cisternae) that folds, chemically modifies, and packages proteins into vesicles for transport around the cell.
What are the two main functions of the Golgi complex?
Correctly folding and chemically modifying newly synthesized cellular products
Packaging proteins into vesicles for trafficking around the cell
Define lysosome.
A lysosome is a membrane-enclosed sac containing hydrolytic enzymes that digest material; it breaks down cellular waste, destroys pathogens, and carries out programmed cell death (apoptosis).
True or False?
In plant cells, a large permanent vacuole helps maintain turgor pressure.
True.
In plant cells, a specialized large vacuole stores water and nutrients, maintaining turgor pressure by pushing against the cell wall.
How does the structure of a mitochondrion relate to its function?
A double membrane provides compartments for the metabolic reactions of aerobic respiration
The inner membrane is highly folded into cristae, giving a large surface area so that ATP can be synthesized efficiently
In chloroplasts, membrane-bound compartments called thylakoids stack to form structures called .
In chloroplasts, membrane-bound compartments called thylakoids stack to form structures called grana.
Define chloroplast.
A chloroplast is a double-membrane organelle found in green plants and photosynthetic algae; it is the site of photosynthesis and contains chlorophyll within its thylakoid membranes.
Define ribosome.
Ribosomes are non-membrane subcellular structures, made of ribosomal RNA (rRNA) and protein, that synthesize proteins according to mRNA sequences.
True or False?
Ribosomes are found only in eukaryotic cells.
False.
Ribosomes are found in cells in all forms of life, reflecting the common ancestry of all known life.
Define endomembrane system.
The endomembrane system is a group of membrane-bound organelles and subcellular components (endoplasmic reticulum, Golgi complex, lysosomes, vacuoles, transport vesicles, nuclear envelope, and plasma membrane) that work together to modify, package, and transport polysaccharides, lipids, and proteins.
What are the two main roles of the endoplasmic reticulum (ER)?
Providing mechanical support, helping the cell maintain its shape
Playing a role in intracellular transport
Rough ER is associated with membrane-bound , which allows it to help carry out protein synthesis.
Rough ER is associated with membrane-bound ribosomes, which allows it to help carry out protein synthesis.
What are the functions of smooth ER?
Detoxification of the cell
Lipid synthesis
Define Golgi complex.
The Golgi complex is a membrane-bound structure consisting of a series of flattened membrane sacs that correctly folds and chemically modifies newly synthesized products and packages proteins for trafficking.
How does the mitochondrion's double membrane contribute to its function?
It provides separate compartments for the different metabolic reactions involved in aerobic cellular respiration.
True or False?
The inner membrane of a mitochondrion is highly convoluted, forming folds that enable ATP to be synthesized more efficiently.
True.
The outer membrane is smooth, while the folded inner membrane (cristae) increases the surface area available for ATP synthesis.
Define lysosome.
A lysosome is a membrane-enclosed sac containing hydrolytic enzymes that digest material. Lysosomes also play a role in programmed cell death (apoptosis).
In plant cells, a specialized large vacuole maintains pressure through nutrient and water storage.
In plant cells, a specialized large vacuole maintains turgor pressure through nutrient and water storage.
How do vacuoles differ between plant and animal cells?
Plant cells: a single large vacuole maintains turgor pressure through nutrient and water storage
Animal cells: vacuoles are smaller and more plentiful, storing cellular materials
Define chloroplast.
A chloroplast is a specialized organelle found in plants and photosynthetic algae. It contains a double membrane and serves as the location for photosynthesis.
Define surface area-to-volume ratio.
Surface area-to-volume ratio is the ratio comparing the total surface area of a cell or organism exposed to the environment with its total internal volume.
What happens to the surface area-to-volume ratio as the size of an organism increases?
The surface area-to-volume ratio decreases, because volume increases much more rapidly than surface area as size increases.
As an organism increases in size, its volume increases much more rapidly than its .
As an organism increases in size, its volume increases much more rapidly than its surface area.
True or False?
A high surface area-to-volume ratio increases a cell's ability to exchange materials with its environment.
True.
A high SA:V ratio provides proportionally more surface for exchange, improving the uptake of resources and the removal of waste.
Which functions are improved by a high surface area-to-volume ratio?
obtaining necessary resources, e.g. oxygen, glucose
eliminating waste products, e.g. carbon dioxide, urea
acquiring or dissipating thermal energy
exchanging chemicals with the surroundings
What are the formulae for the surface area and volume of a sphere?
Surface area = 4πr²
Volume = ⁴⁄₃πr³
cells typically have a higher surface area-to-volume ratio and exchange materials more efficiently than larger cells.
Smaller cells typically have a higher surface area-to-volume ratio and exchange materials more efficiently than larger cells.
Why does the surface area-to-volume ratio restrict the maximum size of a cell?
As a cell grows, its SA:V ratio decreases while its metabolic demand increases, so eventually the plasma membrane becomes too small to exchange materials fast enough for the cell's needs.
How can larger cells increase the surface area of their plasma membrane for exchange?
By having complex cellular structures, such as membrane folds (e.g. microvilli), which increase the surface area available for exchange.
Define microvilli.
Microvilli are folds of the plasma membrane that increase the surface area of a cell for absorption, e.g. on gut epithelial cells.
What is the difference between microvilli and cilia?
Microvilli are folds of the plasma membrane that increase surface area for exchange
Cilia are hair-like structures that beat to move fluid past the cell surface
How are root hair cells adapted for the absorption of water and minerals?
Each root hair is a single-celled extension that increases the surface area of the root, increasing the rate at which water and minerals can be absorbed.
True or False?
As the mass of an organism increases, its rate of heat exchange with the environment decreases.
True.
As mass increases, the SA:V ratio decreases, so proportionally less heat is exchanged with the surrounding environment.
What is the relationship between body size and metabolic rate per unit body mass?
Typically, the smaller the organism, the higher its metabolic rate per unit body mass, because a higher SA:V ratio means more heat is lost and must be replaced.
Sign up to unlock flashcards
or