Cell Theory & Microscopy
State the three principles of cell theory.
All organisms consist of cells; cells are the smallest units of life; and all cells arise from pre-existing cells.
What structure contains the DNA in a typical prokaryotic cell?
The nucleoid region.
Which part of a phospholipid is hydrophilic?
The phosphate-containing head.
What is osmosis?
The net movement of water across a selectively permeable membrane from an area of higher water potential to an area of lower water potential.
What type of specialized blood cell transports oxygen throughout the body?
Red blood cell
Name four processes of life carried out by unicellular organisms.
Any four: metabolism, growth, reproduction, response, homeostasis, nutrition, excretion, and movement.
What is the primary function of ribosomes?
Protein synthesis (translation).
Explain why phospholipids naturally form a bilayer when placed in water.
Their hydrophilic heads face the surrounding water, while their hydrophobic fatty acid tails face inward, away from water.
Does simple diffusion require ATP or a transport protein?
Neither. Molecules move directly through the phospholipid bilayer down their concentration gradient without ATP or transport proteins.
What oxygen-carrying protein is found in red blood cells?
Hemoglobin
Why does electron microscopy reveal structures that light microscopy cannot resolve?
Electron microscopy has higher resolving power, allowing scientists to observe finer details of cell ultrastructure.
Compare the form and location of DNA in typical prokaryotic and eukaryotic cells.
Prokaryotes typically have circular DNA located in the nucleoid region. Eukaryotes have linear chromosomes associated with proteins inside a membrane-bound nucleus.
What is the difference between integral and peripheral membrane proteins?
Integral proteins are embedded within the phospholipid bilayer, while peripheral proteins are attached to the membrane surface.
Explain why glucose generally requires a membrane transport protein to enter a cell.
Glucose is relatively large and polar, preventing it from readily passing through the hydrophobic interior of the phospholipid bilayer.
Which specialized human cell contains a tail (flagellum) that allows it to swim toward an egg?
What type of microscope uses electrons instead of light to produce highly detailed images of cell structures?
Electron microscope
Which organelle contains digestive enzymes used to break down waste materials and pathogens?
Lysosome
What type of membrane protein has a carbohydrate chain attached and is involved in cell recognition?
Glycoprotein
What type of membrane transport moves substances against their concentration gradient using energy?
Active transport
Where in the human body are stem cells found that produce new blood cells?
Bone marrow
What is the term for the ability of a microscope to distinguish two closely spaced objects as separate?
Resolution
Which organelle modifies, sorts, and packages proteins into vesicles for transport?
Golgi apparatus
What molecule found in animal cell membranes helps regulate membrane fluidity?
Cholesterol
What type of bulk transport occurs when a cell releases substances outside the cell by fusing vesicles with the plasma membrane?
Exocytosis
What type of stem cell can develop into all body cell types AND extraembryonic tissues, such as the placenta?
Totipotent stem cell