Cellular level of organization

Question 1

is the cell the smallest unit in the organism?

Answer 1

yes

Question 2

What are the main functions of a cell?

Answer 2

• Reproduction; tissue/organ growth, repair and regeneration.
• Individual metabolism that is integrated with the rest of the tissue and (usually) of the organism.
• homeostatic regulation of its microenvironment.

Question 3

what are some cells that have a very limited repertoire in which they respond to the environment?

Answer 3

• muscle cells and neurons.

Question 4

what are examples of cells that seem very autonomous (wide range of behaviours) given a set of stimuli?

Answer 4

• macrophages and neutrophils.

Question 5

outline alanine and its biological structure;

Answer 5

• size 0.5nm
• structural classification; molecular- single unit (amino acid).

Question 6

outline hemoglobin and its biological structure;

Answer 6

size; 6.8nm
structure; molecular- macromolecule (protein).

Question 7

outline ribosome and its biological structure;

Answer 7

size; 18.0 nm
structure; organelle- small, no membrane

Question 8

Outline mitochondria and their biological structure;

Answer 8

1500 nm in length
structure; organelle–> membrane-bound prokaryotic cell.

Question 9

outline erythrocyte and its biological structure;

Answer 9

8000 nm
structure; cell; small anucleate

Question 10

outline a hepatocyte and its biological structure;

Answer 10

20 000 mn
structure; cell; large, metabolically active, nucleated.

Question 11

what are the plasma membrane and membrane-bound organelles?

Answer 11

1. nucleus
2. mitochondria.
3. RER.
4. SER.
5. Golgi body.
6. Peroxisomes and lysosomes.
7. vacuoles and vesicles.

Question 12

what are the metabolic organelles without membranes?

Answer 12

• ribosomes.

Question 13

what are the structural organelles without membranes?

Answer 13

• microfilaments.
• intermediate filaments.
• microtubule structures.
• microtubules and centrosomes.

Question 14

what is a plasma membrane?

Answer 14

• selectively permeable membrane.
• has a phospholipid bilayer; to both hydrophilic and hydrophobic molecules.
• membrane proteins with important functions; regulating transport, signalling inside and outside, maintaining water and electrolyte balance, movement

Question 15

outline the schematic of the cell membrane; components

Answer 15

1. glycoproteins; protein with attached carbohydrate.
2. glycolipid; lipid with a carbohydrate attached.
3. peripheral membrane proteins.
4. integral membrane proteins.
5. cholesterol.
6. channel protein.
7. phospholipid bilayer.

Question 16

What is the nucleus?

Answer 16

• a repository for DNA.
• functions for DNA; DNA contains the instructions needed for an organism to develop, survive and reproduce.

Question 17

what is the nucleolus?

Answer 17

The nucleolus is a spherical structure found in the cell’s nucleus whose primary function is to produce and assemble the cell’s ribosomes. The nucleolus is also where ribosomal RNA genes are transcribed.

Question 18

what is the function of the nuclear membrane?

Answer 18

The critical function of the nuclear membrane is to act as a barrier that separates the contents of the nucleus from the cytoplasm. Like other cell membranes, the nuclear membranes are phospholipid bilayers, which are permeable only to small nonpolar molecules

Question 19

what are the components of the nucleus?

Answer 19

1. nuclear envelope.
2. condensed chromatin.
3. nucleolus
4. nuclear pores.
5. surrounded by the rough ER (cisternae).

Question 20

what is the nuclear envelope?

Answer 20

• The nuclear envelope (NE) is a highly regulated membrane barrier that separates the nucleus from the cytoplasm in eukaryotic cells. It contains a large number of different proteins that have been implicated in chromatin organization and gene regulation.

Question 21

what is chromatin?

Answer 21

• Chromatin refers to a mixture of DNA and proteins that form the chromosomes found in the cells of humans and other higher organisms. Many of the proteins — namely, histones — package the massive amount of DNA in a genome into a highly compact form that can fit in the cell nucleus.

Question 22

what are nuclear pores?

Answer 22

• The nuclear pore is a protein-lined channel in the nuclear envelope that regulates the transportation of molecules between the nucleus and the cytoplasm.

Question 23

what is the endoplasmic reticulum?

Answer 23

• a network of membrane-lined channels that are continuous with the nuclear envelope.

Question 24

what is the function of the rough ER?

Answer 24

• protein synthesis, modification and trafficking.

Question 25

what is the function of the smooth ER?

Answer 25

- lipid synthesis, general metabolic functions (carbohydrate detoxification), calcium physiology.

Question 26

how are ribosomes associated with the rough ER?

Answer 26

- The ribosome that is synthesizing the protein is directly attached to the ER membrane. These membrane-bound ribosomes coat the surface of the ER, creating regions termed rough endoplasmic reticulum or rough ER

Question 27

why is the RER closer to the nucleus than the SER?

Answer 27

- The proximity of the rough ER to the cell nucleus gives the ER unique control over protein processing. The rough ER is able to rapidly send signals to the nucleus when problems in protein synthesis and folding occur and thereby influences the overall rate of protein translation.

Question 28

what is the Golgi apparatus?

Answer 28

- a site of protein modification and carbohydrate synthesis that works together with the ER. - glycoproteins are formed by attaching carbohydrate moieties to proteins that have been transported from the RER. - carbohydrates; ie matric carbohydrates.

Question 29

what is the mitochondrion?

Answer 29

- an organelle with key metabolic functions. - they perform redox reactions that drive the phosphorylation of ADP to ATP. - they are a source of carbon-containing precursors to build other molecules. - heme production. - urea cycle. - intracellular calcium homeostasis.

Question 30

what are the components of the mitochondrion?

Answer 30

1. the double-membrane structure. inner, membrane (cristae), intermembrane and outer membrane. 2. intermembrane space; hydrogen ions. 3. matric. - all of these structures have key and distinct roles in overall mitochondrial function. - The membranes create two compartments. The intermembrane space, as implied, is the region between the inner and outer membranes. It has an important role in the primary function of mitochondria, which is oxidative phosphorylation. The matrix contains the enzymes that are responsible for the citric acid cycle reactions.

Question 31

what are lysosomes?

Answer 31

- the main site of intracellular degradation for a wide range of molecules. - highly acidic interior and enzymes that are most effective at low pH.

Question 32

what are peroxisomes?

Answer 32

- perform oxidation reactions that remove harmful molecules and aid in the beta-oxidation of fats.

Question 33

what are vesicles?

Answer 33

- vesicles have transport functions; proteins form the RER to the Golgi apparatus then exocytosis. - perform endocytosis in an endocytic vesicle which fuses with a lysosome. - vacuoles have storage functions; fat vacuoles in adipocytes.

Question 34

outline the role of vacuoles in adipocytes.

Answer 34

- adipocytes store triglycerides in a vacuole that occupies the vast majority of the intracellular space.

Question 35

What is the ribosome?

Answer 35

- organelle without a membrane that uses mRNA to accomplish protein translation. - free in the cytosol= translation of cytosolic proteins. - attached to the rER= translation of proteins that will be modified and transported within the rER.

Question 36

outline the ribosome in action;

Answer 36

1. the large and small ribosomal units associate with a stand of mRNA. 2. the ribosomal subunit translates the 3-nucleotide codon into an amino acid with the help of tRNA. codons are also found on DNA.

Question 37

outline the cytoskeleton; structures and functions.

Answer 37

microtubules; - trafficking of organelles and cell division. - organization of overall cellular structure. - cellular movement. - molecule; tubulin. Microfilaments; - cellular movement, - structural organization of the plasma membrane. - molecule; actin. intermediate filaments; - the overall structural integrity of the cell. - the variety of molecules; keratins and desmin.

Question 38

outline the cytoskeleton in an idealized epithelial cell.

Answer 38

- Actin filaments are responsible for the shape of the microvilli. - desmin is organized to provide strength across the cell. - the microtubules have a (-) and (+) end this influences the shape of the cell because they are polar molecules--> helping to arrange other molecules around the cell.