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Bio 131 Exam 1 > Wk2 Lecture 2 Ch 7.2, 7.4. 7.5, 7.6 > Flashcards

Wk2 Lecture 2 Ch 7.2, 7.4. 7.5, 7.6 Flashcards

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Biology 101 flashcards
1
Q

How many membranes does the nuclear envelope have?

A

2, each consists of a lipid bilayer

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2
Q

Is the nuclear envelope continuous or separated from the Endoplasmic Reticulum?

A

Continuous

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3
Q

What is the nuclear lamina?

A

A lattice-like sheet of fibrous proteins that surrounds the surface of the nucleus under the nuclear envelope

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4
Q

What does the nuclear lamina do?

A

-Maintains shape of membrane by stiffening its structure
-Provides attachment points for each chromosome

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5
Q

What is the nuclear pore complex?

A

Consists of nuclear pores (made up of 30 proteins), which function as very big doors/gates into and out of the nucleus

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6
Q

What is exported to the cytoplasm from the nucleus?

A

-mRNA
-ribosomes

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7
Q

Where are mRNA and rRNA/ribosomes synthesized? What is each item’s purpose?

A

In the nucleus; ribosomal RNAs are manufactured in nucleolus to form ribosomes, and mRNA carries info to manufacture proteins.

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8
Q

What is imported to the nucleus?

A

-Proteins for copying DNA, synthesizing RNA, or assembling ribosomes
-DNA/RNA building blocks

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9
Q

How do proteins and other large molecules enter the nucleus? Does that process take energy?

A

Nuclear localization signals - think IDs and bouncers; yes, it is an energy-demanding process

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10
Q

How are proteins produced?

A
  1. Synthesis of mRNA from DNA occurs in the nucleus
  2. mRNA moves to cytoplasm via nuclear pores
  3. Protein synthesized by ribosome from mRNA code

i.e. Central dogma (DNA -> RNA -> Protein)

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11
Q

What is the ER signal sequence?

A

A signal made by a free ribosome that guides growing proteins (destined for secretion/embedded in membranes) + associated ribosome to the rough ER. Present in the first 20 amino acid residues and is removed when protein synthesis is complete.

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12
Q

What is the SRP (signal recognition particle)?

A

A complex of RNA and protein that binds to the ER signal sequence (causing protein synthesis to stop.

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13
Q

How do proteins enter the endomembrane system?

A
  1. Protein synthesis begins on free ribosome, which synthesizes ER signal sequence using mRNA
  2. ER signal sequence binds to SRP, which stops protein synthesis
  3. Ribosome + ER signal sequence + SRP complex move to rough ER membrane, where it attaches to SRP receptor
  4. Receptor and SRP connect => SRP released and protein synthesis continues through a translocon channel
  5. Growing protein is fed into ER lumen or remain associated w/ membrane as integral membrane proteins, and ER signal sequence is removed
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14
Q

How are proteins transported in the endomembrane system?

A
  1. Ribosome deposits protein in ER
  2. Protein exits ER via vesicle made from ER membrane towards cis face of Golgi
  3. Protein enters Golgi for processing/further modifications
  4. Protein exits Golgi via vesicle from trans face towards plasma membrane
  5. Protein secreted from cell
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15
Q

What is the endoplasmic reticulum a site of?

A

Site of synthesis (proteins and lipids), processing, and storage (calcium storage in smooth ER)

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16
Q

What is glycosylation?

A

The addition of one or more carbohydrate groups to a molecule

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17
Q

What is a glycoprotein?

A

Any protein w/ one or more covalently bonded carbohydrates

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18
Q

What is the purpose of carbohydrates on a glycoprotein?

A

They change structure as the proteins are folded, which indicates shipment to the Golgi

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19
Q

What is the Golgi Apparatus a site of?

A

Protein processing, sorting, and shipping

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20
Q

How are products shipped from Golgi Apparatus?

A

Each protein that leaves Golgi has a molecular tag => tag places protein in a particular type of transport vesicle => allows proteins to be shipped to compartments where they function

  1. Proteins are tagged
  2. Proteins are sorted
  3. Vesicles bud
  4. Proteins interact with receptors
  5. Delivery
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21
Q

What is mannose-6-phosphate?

A

A tag on lysosome-bound proteins consisting of a phosphate group attached to a specific sugar on the surface. No mannose-6-phosphate on protein => protein not transported to lysosome

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22
Q

What does the presence of mannose-6-phosphate target proteins to?

A

Organelles that eventually become lysosomes => endosomes

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23
Q

What are proteins in vesicles known as?

A

Cargo

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24
Q

What are vesicles carrying proteins known as?

A

Trucks

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25
Q

Which cells have lysosomes?

A

Animal cells

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26
Q

What are lysosomes?

A

Recycling centers (digestion and waste processing)

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27
Q

What are the three methods of directing material to the lysosome for recycling?

A
  1. Receptor mediated endocytosis
  2. Autophagy
  3. Phagocytosis
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28
Q

What is pinocytosis?

A

The ingestion of extracellular fluid into cell via budding of small vesicles from plasma membrane.

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29
Q

Describe steps of receptor mediated endocytosis (forming a lysosome)

A
  1. Macromolecules from outside cell bind to receptors
  2. Endocytic vesicle forms
  3. Endocytic vescile fuses with early endosome (organelle); proton pumps lower pH
  4. Increasing acidity of early endosome causes it to mature into the late endosome, which is the pre-lysosomal compartment.
  5. Acid hydrolases (digestive enzymes) are dropped off by vesicles from the Golgi
  6. Late endosome => lysosome, which digests the macromolecules
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30
Q

How is cellular (intra and extra) material recycled in the lysosome?

A

Autophagy and phagocystosis

31
Q

Describe steps of autophagy

A
  1. Damaged organelles are enclosed within an internal membrane called the autophagosome
  2. Autophagosome is delivered to lysosome and fuses with it
  3. Components of organelle are digested and recycled
32
Q

Describe steps of phagocytosis

A
  1. Detection-plasma membrane of a cell surrounds a smaller cell/food particle
  2. Plasma membrane engulfs it, creating a phagosome
  3. Phagosome delivered to lysosome
  4. Phagosome is digested and small molecules recycled
33
Q

Common result of all lysosomal digestion/recycling?

A

Molecules are hydrolyzed and the products are transported across the lysosomal membrane into the cytosol for recycling.

34
Q

What is the cytoskeleton?

A

A dense and complex network of fibers that help maintain cell shape by providing structural support

35
Q

Is the cytoskeleton static or dynamic?

A

Dynamic

36
Q

What do the fibrous proteins of the cytoskeleton do?

A
  1. Alter the cell’s shape
  2. Shift its contents (like train tracks)
  3. Even move the cell itself (ex: organelles like the mitochondria)
37
Q

What are the three major types of cytoskeletal elements in eukaryotic cells?

A
  1. Actin filaments
  2. Intermediate filaments
  3. Microtubules
38
Q

What are actin filaments?

A

-The smallest cytoskeletal elements formed by polymerization of individual actin molecules
-Grouped together into long bundles or dense networks
-Have positive and negative ends

39
Q

Where are actin/micro filaments usually found?

A

Just inside plasma membrane

40
Q

Actin/micro filaments are structures that…

A

Help define the cell’s shape

41
Q

Actin function

A

-Structural support
-Movement

42
Q

What is myosin?

A

A motor protein- converts chemical energy from ATP into kinetic energy

43
Q

How does actin work with myosin?

A

Actin is the rope, and myosin is the ratchet that attaches to it and moves (pulls), making the actin filament slide (sailor pulling rope)

44
Q

What direction does myosin pull towards?

A

Negative to positive end of actin filament

45
Q

What cell movements are caused by the ATP-powered interaction b/t actin and myosin?

A

CYTOKINESIS (final stage of cell division to form two cells) and CYTOPLASMIC STREAMING (directed flow of cytosol and organelles within plant and fungal cells)

46
Q

What are intermediate filaments?

A

A long fiber composed of one of various proteins used for structural support (not involved in movement); no polar ends

47
Q

What are intermediate filaments defined by?

A

Size (not composition)

48
Q

Most familiar intermediate filament?

A

Keratin (make up skin, hair, nails, and line surfaces inside body) and Nuclear Lamins (make up nuclear lamina layer)

49
Q

What are microtubules?

A

Paths of the cell; large hollow tubes made of tubulin dimers (alpha and beta tubulin [polypeptides])

50
Q

What does the polarity of a microtubule mean?

A

It has direction

51
Q

Why are microtubules polar?

A

They have plus and minus ends

52
Q

Which tubulin is at each end of a microtubule?

A

alpha tubulin is at minus end

beta tubulin is at plus end

53
Q

Which end do microtubules grow from? (faster)

A

Their plus ends (grow faster)

54
Q

Where do microtubules originate from?

A

The microtubule organizing center; plus ends of microtubules grow from MTOC, radiating throughout cell

55
Q

What is the MTOC of an animal cell called? What is it made of?

A

Centrosome; consist of two bundles of microtubules, called centrioles, surrounded by shapeless matrix of proteins that help initiate growth of new microtubules

56
Q

Microtubule function

A

-Stability
-Involved in movement
-Provides structural framework for organelles
-Railroad tracks (transport vesicles move through the cell along these tracks in energy dependent process)

57
Q

What is kinesin?

A

A motor protein with a head region that binds to the microtubule and a tail region that binds to the transport vesicle

58
Q

How does kinesin allow for movement of vesicles towards the plus end along microtubules during transport from trans-Golgi to plasma membrane?

A

The domains (microtubule and transport vesicle) it binds to allow it to “walk” along the microtubule through a series of conformational changes (as it hydrolyzes ATP); moves towards plus end of microtubules

59
Q

What are flagella?

A

Long, hairlike projections from the cell surface that move cells

60
Q

Eukaryotic v Prokaryotic flagella

A

EUKARYOTIC:
-consists of several microtubules
-surrounded by plasma membrane
-whiplike movement

PROKARYOTIC:
-consists of single helical rod
-not surrounded by plasma membrane
-propellor-like movement

61
Q

What are cilia?

A

Short, filament like projections that help move cell and circulate fluid/particles around surface of stationary cell

62
Q

What is the axoneme of cilia and flagella?

A

A complex “9+2” arrangement of microtubules connected by links and spokes that describes the anatomical structure of cilia and flagella.

63
Q

What does “9+2” arrangement of the axoneme mean?

A

The axoneme has 9 microtubule doublets (pairs) surrounding two central microtubules

64
Q

What is the basal body?

A

Identical in structure to a centriole (9 microtubule triplets arranged in a circle) and serves as an MTOC for growth of the axoneme doublets

65
Q

What is dynein?

A

A motor protein that forms the arms between doublets => hydrolyzed ATP causes bending (of cilia or flagella)

Changes shape when ATP is hydrolyzed to “walk” up the microtubule => shape changes move dynein towards minus end

66
Q

What are the 4 major types of organic molecules/macromolecules?

A
  1. Carbohydrates
  2. Lipids
  3. Proteins
  4. Nucleic Acids
67
Q

What are the 2 main reactions for building and breaking down of molecules?

A
  1. Synthesis - anabolic
  2. Decomposition - catabolic
68
Q

When does synthesis occur?

A

Occurs when atoms, ions, or molecules combine to form new, larger molecules

69
Q

What is anabolism?

A

Synthesis of molecules in a cell

70
Q

When does decomposition occur?

A

Occurs when a molecule is split into smaller molecules, ions, or atoms

71
Q

What is catabolism?

A

Decomposition reactions in a cell

72
Q

What is dehydration synthesis?

A

Monomers covalently bond together to form a polymer through the removal of a water molecule (think sticky part of enelope) - hydroxyl removed from one monomer, hydrogen from the next

73
Q

What is hydrolysis?

A

Splitting a polymer (lysis) by the addition of water (hydro) - a covalent bond is broken

Bio 131 Exam 1 (6 decks)

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