L3: CELL STRUCTURE AND FUNCTION Flashcards
What is the plasma membrane made of?
The plasma membrane is a semipermeable phospholipid bilayer that defines the boundary of a cell.
What factors affect the permeability of the plasma membrane?
The permeability depends on the proteins embedded in the membrane, which have hydrophobic regions.
What does the “fluid mosaic model” describe?
The “fluid mosaic model” describes the lateral movement of membrane components (proteins and lipids).
Can water diffuse through the plasma membrane?
Yes, water can diffuse through the membrane because it is small, even though it is polar.
Can oxygen diffuse through the plasma membrane?
Yes, oxygen can diffuse through because it is non-polar.
Can amino acids diffuse through the plasma membrane?
No, amino acids are large and polar, so they cannot diffuse through easily.
Can glucose diffuse through the plasma membrane?
No, glucose is large and polar, so it cannot diffuse through the plasma membrane.
Can ions diffuse through the plasma membrane?
No, ions are charged and cannot diffuse through the plasma membrane.
What do prokaryotic cells lack?
Prokaryotic cells lack internal membrane-bound organelles.
What covers the plasma membrane of prokaryotic cells?
The plasma membrane of prokaryotic cells is covered by a cell wall.
What does the cytosol in prokaryotic cells contain?
The cytosol contains proteins and nucleic acids in prokaryotic cells.
How do prokaryotic cells compare in size to eukaryotic cells?
Prokaryotic cells are much smaller than eukaryotic cells.
What is the difference between cytoplasm and cytosol?
The cytoplasm includes all the contents of the cell minus the nucleus, while the cytosol is the part of the cell minus all organelles.
What is contained in the nucleus of a cell?
The nucleus contains the cell’s DNA, which holds genetic information.
What is the nuclear envelope?
The nuclear envelope is a double membrane surrounding the nucleus, containing nuclear pores.
What is the role of nuclear pores?
Nuclear pores allow molecules to move in and out of the nucleus.
How is DNA in the nucleus packaged?
DNA in the nucleus is packaged with proteins to conserve physical space.
What is the function of the ER?
The ER is where proteins and lipids are made.
How is the ER connected to the nucleus?
The ER has a single membrane connected to the nuclear envelope.
What is the internal space of the ER called?
The internal space of the ER is called the lumen.
What is unique about the rough ER?
The rough ER has ribosomes studding its surface, which synthesize proteins to be transported around the cell.
What do free-floating ribosomes do?
Free-floating ribosomes make proteins that remain in the cytosol.
How is the smooth ER different from the rough ER?
The smooth ER lacks ribosomes and is involved in marking portions where vesicles bud off to transport proteins and lipids.
What is the function of the Golgi apparatus?
The Golgi apparatus directs proteins and lipids produced by the ER to their final destinations and adds chemical groups to them.
How does the Golgi apparatus look?
The Golgi apparatus consists of a series of flattened membrane sacs surrounded by many small vesicles.
How are proteins transported between the ER and Golgi?
Vesicles transport proteins from the ER to the Golgi and between the sacs of the Golgi.
What are lysosomes?
Lysosomes are vesicles that contain enzymes used to break down sugars, proteins, and fats.
What is the pH of the lumen of lysosomes?
The lumen of lysosomes is acidic, with a pH of about 5.
How do molecules reach lysosomes?
Molecules are delivered to lysosomes by vesicles.
What is the function of vacuoles?
Vacuoles are organelles found in plants and fungi, and they can store water and nutrients or perform functions similar to lysosomes.
What is the function of mitochondria?
Mitochondria are the “power plants” of the cell; they use chemical reactions to break down sugar and produce ATP (cellular respiration).
How are mitochondria structured?
Mitochondria are pod-shaped organelles surrounded by a double membrane.
What is the function of chloroplasts?
Chloroplasts capture energy from the sun to produce sugar through photosynthesis, using CO2 and water. Oxygen is a waste product.
How are chloroplasts structured?
Chloroplasts have a double membrane, and thylakoids inside contain chlorophyll.
What is the function of the cytoskeleton?
The cytoskeleton provides dynamic support to the cell, maintaining cell shape and helping with organelle distribution.
What are microtubules?
Microtubules are polymers of the protein tubulin that can grow or shrink in length by adding or losing tubulin units.
What are actin filaments?
Actin filaments are polymers of actin that can change length by adding or removing actin units.
What do actin filaments do?
Actin filaments are involved in cell movement and form networks that help cells move, such as in pseudopodia
