Chapter 3 - Part 1

Question 1

1. What are the basic concepts of the cell theory?

Answer 1

• Each cell maintains homeostasis
• Cells are the building blocks of all organisms
• All cells come from the division of preexisting cells
• Cells at the smallest units that carry out life’s essential physiological functions.

Question 2

2. What is the difference between sex cells and somatic cells?

Answer 2

• Sex cells - Are reproductive cells (sperm / ova)

- Somatic cells - All other cells in the body

Question 3

3. What are the four functions of the plasma membrane? List and briefly describe each one.

Answer 3

• Physical isolation - physical barrier that separates the inside of the cell
• Regulation of exchange with the environment - Controls entry of ions and nutrients, elimination of waste, and the release of secretions
• Sensitivity to the environment - First part of the cell affected by changes in composition, concentration, or pH of extracellular fluid
• Structural support - Gives tissue stability

Question 4

4. Give the functions of each of these components in the plasma membrane:
   a. Membrane lipids
   i. What role do the phospholipids play in the membrane?

ii. What role does cholesterol play in the membrane?

Answer 4

A. Physical barrier that separates the inside of the cell

B. Stiffens the plasma membrane making it less fluid and less permeable

Question 5

4. Give the functions of each of these components in the plasma membrane:

Membrane proteins – list and briefly describe the 6 types.

Answer 5

1. Anchoring proteins - Attach the plasma membrane to other structures and stabilize its position.
2. Recognition proteins - Immune system cells - recognize other cells as normal or abnormal
3. Enzymes - Catalyze reactions in the extracellular fluid or in the cytosol
4. Receptor proteins - Sensitive to ligands - binding trigger changes in the activity of the cell
5. Carrier proteins - Bind solutes and transport them across the plasma membrane
6. Channels - Central pore - forms a passageway completely through the plasma membrane

Question 6

4. Give the functions of each of these components in the plasma membrane:

Membrane carbohydrates – list and briefly describe the 4 functions of the glycocalyx.

Answer 6

1. Lubrication and protection - Forms a viscous layer that lubricates and protects the plasma membrane
2. Anchoring and locomaotion - Help anchor the cell in place. Movement of specialized cells
3. Specificity in binding
4. Recognition - Cells involved with immune response glycoproteins and glycolipids as normal or abnormal

Question 7

6. What is the definition of cytoplasm?

Answer 7

A general term for the material between the plasma membrane and the membrane that surrounds the nucleus

Question 8

7. What are the differences between the cytosol and the extracellular fluid?

Answer 8

1. Sodium and potassium concentrations differ - potassium higher in cytosol - sodium higher in extracellular
2. Suspended protein concentrations differ - Cytosol contains more
3. Nutrient concentrations differ - cytosol usually is small

Question 9

8. Give the functions of the following non-membranous organelles:

Cytoskeleton

Answer 9

Gives the cytosol strength and flexibility

Support for organelles

Keep them in their proper position

Question 10

Give the functions of the following non-membranous organelles:

Microfilaments

Answer 10

Anchor the cytoskeleton

Determine the consistency of the cytosol (interacting with other proteins)

Question 11

Give the functions of the following non-membranous organelles:

Microtubules

Answer 11

Forms the main portion of the cytoskeleton

Change the shape of the cell

Assist in cell movement

More vesicles / organelles within the cell

Question 12

Give the functions of the following non-membranous organelles:

Microvilli

Answer 12

Increase surface area to facilitate absorption of extracellular materials

Question 13

Give the functions of the following non-membranous organelles:

Centrioles

Answer 13

Essential for movement of chromosomes during cell division

Organization of microtubles in cytoskeleton

Question 14

Give the functions of the following non-membranous organelles:

Cilia

Answer 14

A primary cilium acts as a sensor

Motile cillia more materials sperm

Question 15

Give the functions of the following non-membranous organelles:

Flagella

Answer 15

Movement of the cell

Only human cell with flagellum is sperm

Question 16

Give the functions of the following non-membranous organelles:

Ribosome

Answer 16

Protein synthesis

Question 17

9. There are two types of endoplasmic reticulum: smooth and rough. Give the functions of each one

Answer 17

1. Smooth
   a. Synthesis of the phospholipids and cholesterol
   b. synthesis of steroid hormones
   c. synthesis and storage of glycerides
   d. synthesis and storage of glycogen
2. Rough
   a. Fixed Ribosome synthesize proteins
   b. Chemically modified in the RER and packaged for export to the Golgi Apparatus

Question 18

10. List the 4 functions of the Golgi apparatus.

Answer 18

1. Modifies and packages secretions (hormones and enzymes)
2. Adds or removes carbohydrates to or from proteins
3. Renews or modifies the plasma membrane
4. Packages special enzymes within vesicles (lysosomes)

Question 19

12. What is the function of the lysosome?

Answer 19

Intracellular removal of damaged organelles or pathogens

Question 20

13. What is the function of the peroxisomes?

Answer 20

Catabolism of fats and other organic compounds

Neutralization of toxic compounds generated in the process.

Question 21

14. What is the function of the mitochondria?

Answer 21

Produces 95% of the ATP required by the cell

Question 22

15. Give the function of the following components of the nucleus:

nuclear envelope

Answer 22

Separates the nucleus from the cytosol

Question 23

Give the function of the following components of the nucleus:

Nuclear pore

Answer 23

Chemical communication between the nucleus and cytoplasm

Regulates transport of materials

Question 24

Give the function of the following components of the nucleus:

Nucleoli

Answer 24

rRNA synthesis and assembly of ribosomal subunits

Question 25

16. The nucleus contains DNA. What is the function of the DNA?

Answer 25

Stores instructions for protein synthesis

Question 26

17. What is the difference between chromatin and chromosomes?

Answer 26

Chromatin - nucleosomes are loosely coiled, forming a tangle of filaments Chromosomes - chromatin coils tighter, becoming chromosomes (during cell division)

Question 27

The _______________________ ________________ is the chemical language the cell uses to make proteins in the human body. The information is stored in a sequence of base nucleotides. The nitrogenous bases for DNA include _______________, __________________, ___________________, and ________________________. Base nucleotides are read 3 at a time as a triplet. Each triplet represents one __________________ ________________. A ____________ is the functional unit of heredity and contains enough nucleotides to code for a protein.

Answer 27

Genetic code adenine thymine cytosine guanine Amino acid gene

Question 28

21. Each gene that is to be read has a “start” region called the _________________ and each gene ends with a ___________ signal.

Answer 28

Promoter Stop

Question 29

22. Define transcription. In what location of the cell does this process take place?

Answer 29

Synthesis of RNA from a DNA template Nucleus

Question 30

23. What is the functional role of RNA polymerase during transcription?

Answer 30

Promotes hydrogen bonding Begins as a start signal

Question 31

24. Protein synthesis depends on the Law of Complimentary Base Pairing which states that the base Cytosine always combines with Guanine and Thymine always combines with Adenine in DNA and Uracil in RNA. Given the strand of DNA below, give the strand of RNA that would be produced from that DNA sequence. T A C G G C A C T G C A

Answer 31

AUGCCGUGACGU

Question 32

25. A series of three base nucleotides on the coding strand of DNA is called a triplet. The complementary series of three base nucleotides on the mRNA strand is called a ____________. The complementary series of three base nucleotides on a tRNA is called an _________________.

Answer 32

Codon Anticodon

Question 33

26. Define translation. In what location of the cell does this process take place?

Answer 33

Formation of a linear chain of amino acids, a polypeptide, using the information from a mRNA strand Cytoplasm

Question 34

List the three major phases in translation. Briefly describe each phase.

Answer 34

1. Initiation - Begins as the mRNA strand binds to a small ribosomal subunit as the start codon. The attachment of tRNA and the subsequent binding of the large ribosomal subunit creates a functional ribosome, with the mRNA nestled in the gap between the small and the large ribosomal subunits. 2. Elongation - Amino acids are added to the growing polypeptide chain. As the ribosome moves along the mRNA strand. Translation proceeds swiftly, produces a protein in 20 seconds. 3. Termination - Elongation ends when the ribosome reaches the stop codon at the end of the mRNA strand. The mRNA stays intact and can interact with other ribosomes to create additional copies of the same polypeptide chain.

Question 35

28. Clinical Note: What is a mutation? What are some examples of point mutations?

Answer 35

Permanent changes in the cells DNA that affects the nucleotide sequence of one or more genes. Certain cancers, thalassemia, and sickle cell amina

Question 36

29. Turn to page A-4 in the appendix of your textbook. This is a chart that gives the amino acids coded for on the mRNA codons. Given the template strand of DNA below, provide the base nucleotide sequences for the following: T A C A A A C G G T G T A C T a. Coding strand of DNA: b. mRNA formed: c. Anticodons of tRNA: d. Amino acid sequence: Don't need to remember

Answer 36

A. ATGTTTGCCACATGA B. UACAAACGGUGUACU C. AUGUUUGCCACAUGA D. Start, Phenylalaninel, Alanine, Threoninel, Stop