WEEK 1: EUKARYOTIC CELL Flashcards

1
Q

What are cells?

A

Cells are highly organized, living blocks of the body.

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2
Q

State the three major parts of a cell.

A

Plasma membrane, the nucleus and the cytoplasm

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3
Q

State all parts that make up the cytoplasm.

A

Cytosol, organelles, cytoskeleton

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4
Q

What is a gel-like liquid within which the organelles and cytoskeleton are suspended called?

A

Cytosol

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5
Q

What are organelles?

A

They are discrete, well structures that carry out specialized functions.

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6
Q

What is the scaffolding that extends throughout the cell and serves as the cell’s “bone and muscles?”

A

Cytoskeleton

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7
Q

State the principles of the cell theory.

A

-The cell is the smallest structural and functional unit capable of carrying out life processes

-The functional activities of each cell depend on the specific structural properties of the cell

-Cells are the living building blocks all multicellular organisms

-An organism’s structure and function ultimately depend on the collective structural characteristics and functional capabilities of its cells

-All new cells and new life arise only from pre-existing cells

-Because of its continuity of life, the cells of all organisms are fundamentally similar in structure and function

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8
Q

It is a thin membranous structure that encloses each cell and is composed mostly of lipid (fat) molecules and studded proteins.
What structure is this?

A

Plasma membrane

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9
Q

State the functions of the plasma membrane.

A

-It keeps the ICF within the cell from mingling with the ECF outside the cell
-It allows for selective control of movement of molecules between the ICF and the ECF
-Is involved in endocytosis and exocytosis
-Is involved in cell signaling

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10
Q

What is the doubled-layered membrane that separates the nucleus from the rest of the cell?

A

nuclear envelope

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11
Q

What are the piercings on the nuclear envelope called?

A

Nuclear pore

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12
Q

What are the functions of the DNA?

A

-Direct protein synthesis
-Serves as the genetic blueprint of the cell

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13
Q

Describe the 3 types of RNA that play a role in protein synthesis

A

*Messenger RNA: Exits the nucleus through the nuclear pores and delivers the coded message to ribosomes.

*Ribosomal RNA: protein synthesis – in binding to messenger RNA and transfer RNA to ensure that the codon sequence of the mRNA is translated accurately into amino acid sequence in proteins.

*Transfer RNA: delivers the appropriate amino acids within the cytoplasm to their designated site in the protein under construction.
-temporary carriers of amino acids, bringing the appropriate amino acids to the ribosome based on the messenger RNA (mRNA) nucleotide sequence.

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14
Q

State the 2 categories of organelles.

A

*Membranous organelles- are separate compartment within the cell that is enclosed by a membrane similar to the plasma membrane.

*Non-membranous organelles: Are not surrounded by membrane and thus are in direct contact with the cytosol.

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15
Q

State the 5 main types of membranous organelles.

A

*The endoplasmic reticulum
*Golgi complex
*Lysosomes
*Peroxisomes
*Mitochondria

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16
Q

What is the function of the ER?

A

It is a protein and lipid production factory

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17
Q

State the two types of ER

A

*Smooth ER
*Rough ER

18
Q

Describe the rough ER

A

It consists of stacks of relatively flattened interconnected sacks

19
Q

Describe the smooth ER

A

It is a meshwork of tiny, interconnected tubules.

20
Q

State the 2 main features of the rough ER

A

*Its outer surface is studded with ribosomes
*It also contains enzymes essential for the synthesis of lipids needed to produce new membranes

21
Q

What is the function of rough ER?

A

synthesizes proteins for secretion and membrane construction

22
Q

What is the function of smooth ER?

A

It packages new proteins into transport vesicles.

23
Q

State the destination of proteins synthesized by the rough ER

A
24
Q

Describe the Golgi complex.

A

It consists of stack of flattened, slightly curved, membrane enclosed sacs which do not come into contact with one another, are thin in the middle and dilates at the edges.

25
Q

State the functions of the Golgi complex.

A

*Process the raw materials into finished products
*Sorting and directing the finished products to their final destinations
*Packages secretory vesicles for release by exocytosis

26
Q

Describe how the Golgi complex sort and direct finished products to the proper destinations.

A

1.Finished products collect within the dilated edges of the Golgi complex’s sacs.
2.The edge of the outermost sac then pinches off to form a membrane enclosed vesicle containing a selected product.
3.Vesicles with their selected cargo destined for different sites are wrapped in membranes containing different surface proteins.
4.Each type of surface protein acts as a specific DOCKING MARKER
5.Another protein, a DOCKING MARKER RECEPTOR located only on the proper site of function.
6.The DOCKING MARKER will bind to the specific DOCKING MARKER RECEPTOR IN A lock-and-key fashion and unload the contents of the vesicle.
7.Secretory vesicles bud off from the Golgi stacks and store the secretory proteins until the cell is stimulated by a specific signal that indicates a need for release of that particular secretory product.
8.On appropriate signal, a vesicle moves to the periphery of the cell fuses with membrane, opens and empties its content to the outside (EXOCYTOSIS)

27
Q

What are lysosomes?

A

They are small membrane enclosed, degradative organelles that break down organic molecules.

28
Q

Describe lysosomes formation and structure.

A

1.Are formed budding from the Golgi complex.
2.Contain 40 different hydrolytic enzymes synthesized from the ER, then transported to the Golgi complex for packaging in the budding lysosome

29
Q

Lysosomes digest extracellular material brought into the cell by phagocytosis.

Name the mechanism in which these materials are taken into the cell.

What is the process in which they are digested with called?

Outline extracellular materials that can be digested by lysosomes.

What is the other term used to refer to the digestive function of the lysosomes?

A

1.Phagopcytosis, a type of Endocytosis
2.Hydrolysis
3.Bacteria, Cell debris
4.Intracellular digestive system

30
Q

Outline the 3 ways in which endocytosis can be accomplished.

A

Pinocytosis
Receptor mediated endocytosis
Phagocytosis

31
Q

Describe what happens in pinocytosis.
What is the vesicle taken up into the cell called?

A

A droplet of ECF is taken up non selectively.

*The membrane pockets inward, enclosing solute molecules and water molecules form the ECF

*The pocket then pinches off as ENDOLYTIC VESICLE or ENDOSOSME containing sample of ECF.

32
Q

Describe what happens in receptor mediated endocytosis.

What is the endocytosed vesicle called?

Name the coat proteins on the inner surface of the plasma membrane that facilitates this process.

A

*It is highly selective; the cell is able to import specific large molecules that it needs from the environment.

1.Substances attach to the membrane receptors

2.Membrane pockets inward

3.Pocket pinches off as an endolytic vesicle containing target molecule.

*Coated pit
*Clathrin

33
Q

Describe what happens in phagocytosis.

A

Only special types of White blood cells are able to carry out phagocytosis.

1.Pseudopods begin to surround the prey and close around it

2.The prey is enclosed in an endolytic vesicle that sinks into the cytoplasm.

3.Lysosome fuses with the endolytic vesicle, releasing enzymes that attack material inside the vesicle.

34
Q

What are peroxisomes?

A

They are membranous organelles that produce and decompose hydrogen peroxide in the process of degrading potentially toxic molecules.

35
Q

Describe what happens in peroxisomes.
Name the main compound formed in the peroxisomes.
How is it degraded?

A

*They contain oxidative enzymes.
*They degrade alcohol and other toxic foreign compounds.
*Hydrogen peroxide is liberated which is converted to water and oxygen as it can be destructive by CATALASE.

36
Q

What is a mitochondria?

A

Are energy organelles of the cell, they extract energy for the nutrients in food and transform it into usable form for cell activities.

37
Q

Describe the structure of a mitochondrion

A

Has 2 membranes; outer and inner mitochondrial membranes

*There is intermembrane space in between the membranes

*/The inner membrane has infoldings called CISTEAE with a gel like solution called MATRIX.

38
Q

What are the functions of the Cristae and matrix of the mitochondrion?

A

Cristae contain proteins that use oxygen to convert energy in food into a usable form.

The folding increase surface area.

Matrix contains different dissolved enzymes that prepare nutrient molecules for final extraction of usable energy by the cristae proteins.

39
Q

What are the functions of ribosomes?

A

Protein synthesis.
Translation of amino acid ordered sequence dictated by DNA code.

40
Q

Differentiate between free ribosomes and Rough-ER ribosomes.

A

*Free ribosomes: Produces proteins for use in cytosol.

*Rough ER ribosomes: Synthesizes proteins for secretion and for construction of new cell components.

41
Q

State the functions of the cytosol.

A

1.Intermediary metabolism: Serves as a medium for chemical reaction to take place such as degradation, synthesis.

2.Contain free ribosomes which synthesize proteins for use in the cytosol.

3.Storage of fat, glycogen and secretory vesicles.

42
Q

Outline the 3 distinct elements of the cytoskeleton and their functions.

A
  1. Microtubules: maintain asymmetric cell shape and play a role in complex cell movements.

2.Microfilament: Are important to cellular contractile system and acts as mechanical stiffeners.

3.Intermediate filaments: Are important in cell regions subject to stress.