What does cell theory state about the composition of living organisms?
All living organisms are composed of cells.
What does cell theory identify as the basic unit of life?
The cell.
From what do new cells arise, according to cell theory?
Pre-existing cells.
What is the plasma membrane?
A selectively permeable phospholipid bilayer with embedded proteins.
Where do ribosomal subunits form, and from what materials?
They form in the nucleolus from rRNA and proteins.
Where do ribosomal subunits assemble into ribosomes?
In the cytoplasm.
What structures form the endoplasmic reticulum?
A network of membranous tubules and sacs called cisternae.
What is the internal compartment of the endoplasmic reticulum called?
The lumen, or cisternal space.
What does the smooth endoplasmic reticulum synthesize?
Lipids.
Which carbohydrate-related process does the smooth endoplasmic reticulum perform?
It metabolizes carbohydrates.
Which ribosomes make proteins secreted by many cells?
Ribosomes attached to the rough endoplasmic reticulum.
How do secretory proteins leave the endoplasmic reticulum?
Inside membrane-wrapped vesicles.
What cellular function do lysosomes help maintain?
Continuous cell renewal.
In which organisms do mitochondria occur?
Eukaryotes, including plants, animals, fungi, and protists.
What determines the number of mitochondria in a cell?
The cell’s metabolic activity.
What is the mitochondrial matrix?
The space enclosed by the inner mitochondrial membrane.
What does the mitochondrial matrix contain?
Enzymes, mitochondrial DNA, and ribosomes.
What are the flattened interconnected sacs inside a chloroplast called?
Thylakoids.
What connects adjacent plant cells through perforations in their cell walls?
Plasmodesmata are channels connecting adjacent plant cells.
What structures are present in plant cells but absent from animal cells?
A cell wall and plastids.
How do plant and animal cells usually differ in size and shape?
Plant cells are larger and square or rectangular; animal cells are smaller and irregular or round.
Where is the nucleus usually located in plant versus animal cells?
Plant cells usually have a side-positioned nucleus; animal cells usually have a central nucleus.
How do vacuoles usually differ between plant and animal cells?
Plant cells have few large vacuoles or one central vacuole; animal cells have small, numerous vacuoles.
How do mitochondria usually differ in number between plant and animal cells?
Plant cells have fewer mitochondria; animal cells have numerous mitochondria.
Which organelles are rare or absent in plant cells but present in animal cells?
Lysosomes are rare and centrosomes are absent in plant cells; animal cells have both.
How does membrane composition differ among organelles?
Each organelle membrane has a unique composition of lipids and proteins.
What structures are present in the nuclear envelope?
Pores.
What are transport vesicles?
Vesicles in transit from one part of the cell to another.
What happens to ER products traveling from the cis to trans side of the Golgi?
They are modified.
Which cellular process do macrophages carry out?
Phagocytosis.
What is cell sap?
The solution inside the central vacuole.
How many membranes enclose a mitochondrion, and what are they made of?
Two phospholipid bilayer membranes.
What shape does a mitochondrion’s outer membrane have?
It is smooth.
Where is the mitochondrial intermembrane space located?
Between the outer and inner mitochondrial membranes.
Which structures do both plant and animal cells have?
A plasma membrane, cytoplasm, nucleus, endoplasmic reticulum, Golgi apparatus, ribosomes, and mitochondria.
Answer 14 questions on Cell Structure and Organelles.
1. Which statement summarizes the three central claims of cell theory?
2. What structure allows the plasma membrane to regulate which substances cross it?
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