2 Cells And Membranes Flashcards

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1
Q

Name all the 6 organelles

A
Nucleus
Endoplasmic reticulum (ER)
Golgi apparatus 
Ribosomes
Mitochondrion
Chloroplast
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2
Q

Function of Nucleus

A

Storage of genetic information

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3
Q

Function of rough Endoplasmic reticulum

A

Folding and modification of polypeptide chains, packaged into transport vesicles

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4
Q

Function of smooth endoplasmic reticulum

A

Synthesis of lipids, carbohydrate metabolism, detoxification of drugs and poison

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5
Q

Function of Golgi apparatus cis face?

A

Received materials from transport vesicles from ER for further modification of proteins

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6
Q

Function of Golgi apparatus trans face?

A

Packages protein into secretory vesicles

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7
Q

Function of ribosomes?

A

Site of polypeptide synthesis.

Bound ribosomes (rough ER) synthesis polypeptides to use outside cell, incorporated in plasma membrane or as lysosomal enzymes

Free ribosomes (cytosol) synthesize polypeptides that forms protein to be used in the cell

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8
Q

Function of the mitochondrion?

A

Site of cellular respiration to produce energy to form a high energy compound adenosine triphosphate (ATP)

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9
Q

Function of chloroplast?

A

Photosynthesis

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10
Q

Structure of nucleus?

A
  1. Double membrane bound nuclear envelope that contains nuclear pores
  2. Aqueous matrix and dense region called nucleolus
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11
Q

Structure of ER? (Smooth and rough)

A

Smooth: extensive network of membranous tubules

Rough: membrane bound sacs

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12
Q

Structure of Golgi apparatus?

A

Flattened membranous sacs

Membrane bound

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13
Q

Structure of ribosomes

A

Bound ribosomes are on the rough ER

they are not membrane bound

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14
Q

Structure of mitochondrion?

A

Elongated/spherical
Double membrane bound outer and inner (high folded)
Contains own circular DNA, ribosomes and enzymes

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15
Q

Structure of chloroplasts

A

Lens-shaped
Double membrane bound outer and inner (no folding)
Third membrane system consisting of flattened sacs called thylakoids
Contains own circular DNA, ribosomes and enzymes

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16
Q

PROTEIN SYNTHESIS PATHWAY

A

1) DNA transcripts into mRNA
2) mRNA transported to rough ER
3) ribosomes on rough ER translate the mRNA into a polypeptide chain, which enters lumen of rough ER for folding and modification
4) folded protein packaged into a transport vesicle that buds off the rough ER
5) transport vesicle enters the vid face of the Golgi apparatus and releases the protein into the Golgi apparatus for further modification and folding
6) product packaged into secretory vesicles that bud off the trans face of Golgi
7) secretory vesicle fuses with cell membrane and secretes folded protein out of cell/ embeds it in the cell membrane/ allow formation of lysosomes

17
Q

What is phagocytosis (formation of lysosomes)

A

Fuses the newly formed vesicles to break down ingested materials

18
Q

What is the ‘fluid mosaic model’ of membranes

A

Mosaic: collage of different proteins randomly embedded in phospholipid bilayer

Fluid: phospholipid are mobile, they move around through rotation, lateral diffusion, flexion and flip flop

19
Q

What are integral proteins

A

Proteins deeply embedded in the hydrophobic core of the bilayer. Embedded in membrane and might be modified

20
Q

What is steroid cholesterol in the phospholipid bilayer

A

It is a major determinant of membrane fluidity and regulates membrane fluidity by restricting movements of phospholipids

21
Q

Functions of membrane proteins?

A

Transport
Enzymatic activity
Signal transduction
Cell-cell recognition

22
Q

Two types of vesicle transport across membrane

A

Endocytosis

Exocytosis

23
Q

Three types of transport protein with membrane protein

A

Diffusion (passive/facilitated)
Osmosis
Active transport

24
Q

What is diffusion across phospholipid bilayer

A

Net movement of molecule from region of higher concentration to a region of lower concentration, down the concentration gradient

25
Q

What molecules can cross through the phospholipid bilayer through passive diffusion

A

Small and relatively hydrophobic molecules

26
Q

What molecules can cross through the phospholipid bilayer through facilitated diffusion

A

Allows polar and charged molecules and ions to cross without interacting directly with the hydrophobic core

27
Q

Describe facilitated diffusion carrier proteins

A

Bind to molecule on one side
Undergo conformational changes
Releases molecule on other side

28
Q

Describe facilitated diffusion channel proteins

A

Form open pores for small particles of appropriate size and change to pass through freely
Gates open to selective stimuli

29
Q

Describe osmosis

A

Net movement of water molecules from a region of higher water potential to a lower … through a partially permeable membrane

30
Q

Describe active transport

A

Movement of ions or molecules across membrane from region of concentration to lower … against concentration gradient

31
Q

What are the two parts of endocytosis

A

Phagocytosis and pinocytosis

32
Q

What is phagocytosis?

A

Ingestion of large particles

-particles bind to surface of phagocyte (receptor), which triggers pseudopod to engulf particle and form a vesicle to transport it.

33
Q

What is pinocytosis?

A

Uptake of fluids/ macromolecules through small vesicles. It is non-selective

  • particles bind to plasma membrane, it folds inwards to form a channel
34
Q

Describe exocytosis

A

Movement of substances out of cell into extra cellular space/ vice versa

  • vesicle containing material transported to cell membrane
  • vesicle membrane fuses with cell membrane and releases contents
35
Q

What factors affect rate of movement?

A
  • size
  • polarity
  • concentration gradient
  • temperature