Bio chapter 3

What is a cell?

A cell is the smallest unit of life.

Which three organelles contain DNA?

DNA occurs in the nucleus, chloroplasts, and mitochondria

How are cilia and flagella similar, and how are they different?

In eukaryotes, cilia and flagella are similar in their internal structure (the 9+2 arrangement of microtubules). Both structures move, but they differ in their length and in how they move. Cilia are short and move in wave-like motions. Flagella are much longer and move with a whiplike motion.

Chemically, how is a phospholipid different from a triglyceride?

A phospholipid has two fatty acids and a phosphate group attached to the glycerol, while a triglyceride just has three fatty acids that attach to the glycerol.

Which organelles are the cell's "recycling centers"?

Lysosomes, vacuoles, and peroxisomes are the cell's recycling centers

How does the chemical structure of phospholipids enable them to form a bilayer in water?

The hydrophilic heads naturally make contact with water while the hydrophobic tails naturally avoid water. When many phospholipids join, the hydrophilic heads and hydrophobic tails align, forming a bilayer.

What are some functions of the cytoskeleton?

The cytoskeleton provides a structural framework for the cell, is a transportation system within the cell, allows the cell to move, and connects cells together.

How have microscopes contributed to the study of cells?

*Microscopes have led to the discovery of cells, *have allowed us to differentiate structures in prokaryotic and eukaryotic cells *have allowed us to study the organelles that make up a eukaryotic cell, * *and have even let us watch some basic cell functions as they occur

In what ways is a prokaryotic cell like a baseball stadium, but a eukaryotic cell is more like an office building?

A prokaryotic cell is more like a baseball stadium because it has a simple structure with few internal compartments. A eukaryotic cell is more like an office building because it is more complex and has many different internal compartments and specialized areas.

Describe adaptations that increase the ratio of surface area to volume in cells.

Adaptations that increase the surface area to volume ratio include elongated or flattened cell shapes. An efficient transportation system, a water-filled vacuole, and improved efficiency help cells sidestep surface area limitations.

Which molecules and structures occur in all cells?

All cells have DNA, proteins, RNA, ribosomes, a watery cytoplasm, and a cell membrane.

List the features that all cells share, then name three structures or activities found in eukaryotic cells but not in bacteria or archaea.

All cells have: DNA, RNA, protein, ribosomes, cytoplasm, and a cell membrane. Structures or activities found only in eukaryotic cells include any of the organelles, a nucleus, or the activities of the endomembrane system.

2. How are bacteria and archaea similar to and different from each other?

Bacteria and archaea are small cells that lack nuclei and membrane-bounded organelles. The two groups differ in the composition of the cell wall and the lipids in the cell membrane.

What functions do cell walls provide?

Cell walls provide rigidity, prevent a cell from bursting if it takes on too much water, and allow interactions with other cells to determine how a cell of a complex plant becomes specialized.

What are some functions of plastids?

Chloroplasts are plastids that carry out photosynthesis. Other plastids store pigments or food, or they help a plant to detect gravity.

What are some functions of membrane proteins?

Membrane proteins have the following functions: - transport proteins move substances into and out of cells; - enzymes facilitate chemical reactions; - recognition proteins on cell surfaces allow the body to recognize its own cells; - adhesion proteins allow cells to stick together; - receptor proteins bind molecules to the outside of the cell and trigger chemical reactions inside the cell

Which organelle houses the reactions that extract chemical energy from nutrient molecules?

Mitochondria house the reactions that extract chemical energy from nutrient molecules.

How do organelles contribute to efficiency in eukaryotic cells?

Organelles contribute to efficiency in eukaryotic cells because they concentrate the biochemicals needed for chemical reactions so that the reactions proceed more rapidly, leading to efficiency. Also, because of organelles, a eukaryotic cell can get along with high concentrations of biochemicals only in certain areas. The biochemicals do not have to be in high concentrations throughout the cell.

Where in the cell do phospholipid bilayers occur?

Phospholipid bilayers occur around organelles within the cell and at the cell's surface as the plasma membrane.

What is the chemical composition of a plant cell wall?

Plant cell walls are made mostly of cellulose but also contain hemicellulose and pectin.

How do plant cells differ from animal cells?

Plant cells have two key organelles that animal cells generally do not have: chloroplasts and vacuoles. Outside of the plasma membrane, plant cells have a cell wall that animal cells lack. Plant cells are connected by plasmodesmata, but lack the other forms of connections found in animal cells.

Which cell types have a cell wall?

Plants, algae, fungi, bacteria and archaea all have cell walls, but the walls are made of different materials.

What are plasmodesmata?

Plasmodesmata are tunnels that connect adjacent cell walls.

How do prokaryotic cells differ from eukaryotic cells?

Prokaryotic cells lack a nucleus and other membrane-bounded organelles, have cell walls made of peptidoglycan, and are typically much smaller than eukaryotic cells.

What are the main components of cell theory?

That all life is made of cells, that cells are the fundamental unit of life, and that all cells come from preexisting cells

Describe the differences between light and electron microscopes?

The light microscope can be used to study living organisms, does not distort structures, can show structures in stained color, and is less expensive than the electron microscope. However, the light microscope lacks much of the magnification and resolution of the electron microscope.

What are the main components of the cytoskeleton?

The major components of the cytoskeleton are microtubules, microfilaments, and intermediate filaments.

What is the function of the nucleus and its contents?

The nucleus contains DNA (the molecule that contains the instructions for making proteins) and the nucleolus (where ribosomes are assembled). mRNA molecules also are present in the nucleus, where they gather information and exit to the cytoplasm through nuclear pores

Which organelles interact to produce and secrete a complex substance such as milk?

The nucleus, ribosomes, smooth ER, Golgi apparatus, and vesicles are organelles involved in the production of milk

What are the three types of junctions that link cells in animals?

Tight junctions, gap junctions, and anchoring junctions link cells in animals.

The simplest viruses consist only of a protein coat surrounding DNA or RNA. What does a simple virus have in common with cells? What does it lack that all cells have?

Viruses share 3 things with cells: DNA, RNA (but not both together), protein. Viruses lack: ribosomes, cytoplasm, and a cell membrane.