Ch.4 Concepts & Connections

Question 1

Describe the importance of microscopes in understanding cell structure and function. 2 parts - 3 types of microscopes

Answer 1

there are 3 different types of microscopes: light microscope, electron microscope, and transmission electron microscope.

Question 2

describe the light microscope

Answer 2

visible light is passed through a specimen (an organism or a thin slice of tissue) and then through glass lenses. can see organisms such as most plant and animal cells, nucleus, most bacteria, and mitochondria (1-100 um)

Question 3

describe the electron microscope

Answer 3

focuses a beam of electrons through a specimen or onto its surface, this high-reso has given opportunity to explore cell ultrastructure, the complex anatomy of a cell. can see the smallest bacteria, viruses, ribosomes, proteins, lipids, small nucleus, atoms(1um - 0.1nm). there is also the scanning electron microscope that is similar to the electron microscope and used to study detailed architecture of cell surfaces

Question 4

describe the transmission electron microscope

Answer 4

used to study the details of internal cell structure. it aims an electron beam through a very thin section of a specimen. this microscope CANNOT be used to study living specimens

Question 5

Describe the two parts of cell theory.

Answer 5

all living things are composed of cells and all cells come from other cells

Question 6

Distinguish between the structures of prokaryotic and eukaryotic cells.

Answer 6

prok: bacteria and archea. do NOT contain a membrane-enclosed nucleus, prokaryotes evolved before eukaryotes.
euk: protists, fungi, plants and animals. contain a membrane-enclosed nucleus which houses most of their DNA

Question 7

Explain how cell size is limited.

Answer 7

a cell must be large enough to house enough DNA, protein molecules and structures to survive and reproduce. the max size of a cell is influenced by geometry - the need to have a surface area large enough to service the volume of a cell.

Question 8

Describe the structure and functions of cell membranes.

Answer 8

the plasma membrane forms a flexible boundary between the living cell and its surroundings

Question 9

Explain why compartmentalization is important in eukaryotic cells.

Answer 9

surface area and volume. surface area to volume ratio: at some point cell size must be limited because simple diffusion takes time

Question 10

Compare the structures of plant and animal cells. Note the function of each cell part.

Answer 10

d

Question 11

Compare the structures and functions of chloroplasts and mitochondria.

Answer 11

mitochondria is found in animal cells and is the power-house of the cell, contains a double membrane, contains the matrix, has its own DNA (mtDNA) and is sensitive to certain toxins. chloroplast is similar to mitochondria and is found in plant cells and functions in energy processing.

Question 12

Describe the evidence that suggests that mitochondria and chloroplasts evolved by
endosymbiosis.

Answer 12

mitochondria and chloroplasts were formerly small prokaryotes that began living with larger cells. evolution: the world was becoming increasingly aerobic from the oxygen generating photosynthesis of prokaryotes, a host cell would benefit from an endosymbiont that was able to use oxygen to release large amounts of energy from organic molecules from cellular respiration

Question 13

Compare the structures and functions of microfilaments and microtubules. (intermediate filaments are not necessary for the exam) fibers of the cytoskeleton

Answer 13

microfilaments: solid rods composed of globular protein called actin arranged in a twisted double-chain, especially important in plant cells and cell movement. it functions like a rope and pulls. microtubuals: straight hollow tubes composed of globular proteins called tubulins. functions as a pipe that can pull and push. *(de)polymorization is the increase or decrease in filament length

Question 14

Relate the structure of cilia and flagella to their functions.

Answer 14

cilia: short numerous (hair like) appendages that propel protists such as parmecium.
flagella: fast and efficient with a whiplike motionthat propels a head-like structure (found in sperm). most cells have cilia and both function in cellular movement

Question 15

Relate the structure of the extracellular matrix to its functions.

Answer 15

functions in support and regulation as well as cellular respiration. the ECM is located in the intermembrane space of the mitochondria where the KREBS cycle occurs and ETC (electrotransport chains). the ECM helps hold the cell together and protext/supports the plasma membrane. main components: glycoproteins, proteins bounded with carbohydrates.

Question 16

Compare the structures and functions of tight junctions and gap junctions (anchoring junctions not important)

Answer 16

tight junctions: prevent leakage of ETF (extracellular fluid) across a layer of epithelial cells, desmosome (held tight in skin). gap junctions: are channels that allow molecules to flow between cells, gut (not so tightly) ameobic dysentry.

Question 17

Relate the structures of plant cell walls and plasmodesmata to their functions. (not important for midterm!)

Answer 17

plasmodesmata serves in communication between cells

Question 18

Describe the four functional categories of organelles in eukaryotic cells.

Answer 18

1.genetic control 2.manufacturing distribution and breakdown 3.energy processing 4.structural support, movement, and communication between cells