ch 3 - quick check

Question 1

what is the molecular composition of the plasma membrane of the cell?

Answer 1

The plasma membrane is two layers that include phosphate-containing fat molecules called phospholipids, which form a fluid framework, and another kind of fat molecule called cholesterol, which assists in the stabilization of the phospholipid molecules to prevent breakage of the plasma membrane. Protein molecules are also embedded within the plasma membrane.

Question 2

what is cytoplasm? what is contained within cytoplasm?

Answer 2

The cytoplasm is the internal living material of cells. It contains organelles such as ribosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, and centrioles.

Question 3

what are the primary organelles of the cell?

Answer 3

cytoskeleton
ribosomes
endoplasmic reticulum
golgi apparatus
mitochondria
lysosomes
centrosome
centrioles
microvilli
cilia
flagella

Question 4

what is the function of the organelle, Cytoskeleton?

Answer 4

Internal framework of the cell

Question 5

what is the function of the organelle, ribosomes

Answer 5

Manufacture enzymes and other proteins and are often called “protein factories”

Question 6

what is the function of the organelle, endoplasmic reticulum (ER)?

Answer 6

Network of connecting sacs and canals that carries substances through the cytoplasm

Question 7

what is the function of the organelle, golgi apparatus?

Answer 7

Collects chemicals into vesicles that move from the smooth endoplasmic reticulum to the plasma membrane (called the “chemical processing and packaging center”)

Question 8

what is the function of the organelle, mitochondria?

Answer 8

Involved with energy-releasing chemical reactions (cellular respiration) and are often called the “power plants of the cell”

Question 9

what is the function of the organelle, lysosomes?

Answer 9

Eat microbes, and the membrane has enclosed packets containing digestive enzymes that promote hydrolysis; often called “digestive bags”

Question 10

what is the function of the organelle, centrosome?

Answer 10

Serves as the microtubule-organizing center of the cell. It is a region of cytoplasm near the nucleus of each cell. It also plays a role in forming and organizing the cell’s cytoskeleton, including some of the cell’s outward extensions.

Question 11

what is the function of the organelle, centrioles?

Answer 11

Paired organelles found within the centrosome. Each centriole is composed of microtubules that play an important role in forming a tapered framework or “spindle” that moves chromosomes during cell division.

Question 12

what is the function of the organelle, microvilli?

Answer 12

Small, fingerlike projections of the plasma membrane of some cells. They increase the surface area of the cell and increase its ability to absorb substances.

Question 13

what is the function of the organelle, cilia?

Answer 13

Extremely fine, hairlike extensions on the exposed or free surfaces of cells. Cilia act like an insect’s antennae, allowing the cell to sense its surroundings such as the cilia in the taste buds of the mouth that allow us to detect different chemicals by taste.

Question 14

what is the function of the organelle, flagella?

Answer 14

Projections extending from the cell surface. In humans, the only example of a flagellum is the “tail” of the male sperm cell.

Question 15

which two kinds of cell structures contain DNA?

Answer 15

Chromatin and chromosomes

Question 16

what is the difference between a passive transport process and an active transport process?

Answer 16

The difference is that active transport requires ATP and passive transport does not.

Question 17

briefly explain the following primary passive transport process: diffusion

Answer 17

Diffusion: A trend of movement of particles down a concentration gradient. This movement occurs from an area of high concentration toward an area of lower concentration.

Question 18

briefly explain the following primary passive transport process: osmosis

Answer 18

A special case of passive transport. In many ways it is similar to diffusion, but it is thought to involve unique mechanisms at the pores of cell membranes. Water moves into a space, but there is no exchange of solutes. Instead a change in fluid pressure may result that is called osmotic pressure.

Question 19

briefly explain the following primary passive transport process: dialysis

Answer 19

Some solutes move across a selectively permeable membrane by diffusion, and other solutes do not. This results in an uneven distribution of various solutes. This principle is used as a medical procedure (dialysis) when a kidney is not functioning properly.

Question 20

briefly explain the following primary passive transport process: filtration

Answer 20

The movement of water and solutes through a membrane as a result of a pushing force that is greater on one side of the membrane than on the other side. This force is called hydrostatic pressure. Filtration always occurs down a hydrostatic pressure gradient.o

Question 21

how does an ion pump work? is it an active or passive transport process?

Answer 21

The ion pump uses energy from ATP to actively move ions across cell membranes against their concentration gradient. It is an active process.

Question 22

how do phagocytosis and pinocytosis differ?

Answer 22

Phagocytosis is the process that allows a cell to engulf and “eat” relatively large particles. An example - white blood cells. to destroy bacteria and debris from tissue damage.
Pinocytosis is an active transport mechanism used to incorporate fluids or dissolved substances into cells by trapping them in a pocket of plasma membrane that pinches off inside the cell.

Question 23

how do genes determine the structure and function of the body?

Answer 23

Genes are specific segments of base pairs in a chromosome. Genes direct the synthesis of one kind of protein molecule that may function in a certain manner.

Question 24

where is genetic information stored in the cell?

Answer 24

Nucleus

Question 25

what are the main steps to making a protein in the cell?

Answer 25

The DNA molecule contains a sequence of base pairs, or genes, that represents a sequence of amino acids. During transcription, the DNA code is transcribed as an mRNA molecule forms. During translation, the mRNA code is “translated” at the ribosome, and the proper sequence of amino acids is assembled. The amino acid strand coils or folds as it is formed. The coiled amino acid strand folds again to form a protein molecule with a specific, complex shape.

Question 26

what are the 4 phases of mitotic cell division?

Answer 26

Prophase, metaphase, anaphase, and telophase

Question 27

what is the interphase period of a cell? what is the importance of this period in the life cycle of a cell?

Answer 27

Interphase is the period of life cycle when the cell is not actively dividing. During interphase and just before mitosis begins, the DNA of each chromosome makes an identical copy of itself. It then enters another growth period of interphase before it begins to actively divide. So although it is said to be “resting,” it is very active and only resting from the standpoint of active cell division.