Module 4 Flashcards
(88 cards)
1
Q
What are three things that differentiate a eukaryotic cell from a prokaryote?
A
- have membrane-bound organelles that perform specific functions
- eukaryotes are more structurally complex
- generally larger
2
Q
What is a membrane-delimited nuclei?
A
when the nucleus is separated by a double layer called the nuclear envelope
3
Q
The ____________ is based on eukaryotic membranes
A
fluid mosaic model
4
Q
Draw a fluid mosaic model rn and label it
A
check notes
5
Q
What are lipid rafts and what is their function?
A
- microdomains found in eukaryotic membranes
- participate in cell processes such as cell movement and transduction
6
Q
What do lipid rafts contain high concentrations of?
A
certain lipids and proteins
7
Q
Where do organelles lie in eukaryotic cells?
A
The cytoplasmic matrix
8
Q
What is the cytoskeleton
A
a vast network of interconnected filaments within the cytoplasmic matrix
9
Q
What filaments form the cytoskeleton?
A
- microfilaments
- microtubules
- Intermediate filaments
10
Q
What does the cytoskeleton do?
A
plays a role in both cell shape and cell movement
11
Q
What are microfilaments and what is their function?
A
- minute acting pr- filaments
- involved in cell motion and shape changes
12
Q
how large are microfilaments and how are they organized?
A
- 4-7nm in diameter
- scattered or organized into networks and parallel arrays
13
Q
What are microtubules and what are their functions?
A
- made of proteins a-tubulin and b-tubulin
- maintain cell shape, cell movement, participate in intracellular transport processes
14
Q
What is the shape and size of microtubules?
A
shaped like thin cylinders
~25nm in diameter
15
Q
What are intermediate filaments and what is their function
A
- heterogeneous
- role is unclear but some form nuclear lamina and others help link cells together to form tissues
16
Q
What are the organelles in secretory and endocytic systems?
A
- endoplasmic reticulum
- golgi apparatus
- lysosomes
17
Q
Describe the process of the secretory pathway
A
- pr- synthesis by ribosomes on the rough ER are released in small vesicles
- go to Cis face of Golgi Apparatus
- go to Trans face of Golgi Apparatus
- Transport vesicles released from Golgi Apparatus
- After release, some deliver to lysosomes, others to cell membrane
18
Q
What is the endoplasmic retuiculum?
A
irregular network of branching and fusing membranous tubules and flattened sacs
19
Q
What are Rough Endoplasmic Reticulum’s?
A
- synthesis of secreted pr-
- have ribosomes attached
20
Q
What are Smooth Endoplasmic Reticulum’s?
A
- synthesis of lipids by ER-associated enzymes
- no ribosomes (that’s why its smooth)
21
Q
What are 3 functions of the ER?
A
- transports pr-, lipids, and other materials within the cell
- major site of cell membrane synthesis
- synthesis of lysosomes
22
Q
What is the Golgi Apparatus and what is its function?
A
- Membranous organelle made of cisternae stacked on each other
- involved in modification, packaging and secretion of materials
23
Q
What are dictyosomes?
A
stacks of cisternae
24
Q
What are lysosomes and what is their function?
A
- membrane-bound vesicles found in most eukaryotes
- involved in intracellular digestion
25
Where are hydrolases found?
In lysosomes
26
What are hydrolases?
enzymes that hydrolyze molecules and function best under slightly acidic conditions
27
How do hydrolases maintain an acidic environment?
they pump protons into their interior
28
How is cellular digestion kept safe from harming the cytoplasm?
digestion occurs inside lysosomes, preventing the release of digestive enzymes into the cytoplasmic matrix
29
What happens to the products of digestion inside lysosomes?
As the contents are digested, the products leave the lysosome and can be used as nutrients by the cell
30
What is the name of a lysosome after digestion is complete?
residual body
31
How can the cell get rid of the contents of a residual body?
A residual body can release its contents to the cell exterior through lysosome secretion
32
What is the function of the Biosynthetic-Secretory Pathway?
It moves materials to lysosomes, and from inside the cell to the cell membrane or exterior
33
How does the cell ensure quality in the Secretory Pathway?
Unfolded or misfolded pr- are secreted into the cytosol, where they are targeted for destruction and broken down
34
What targets the misfolded pr- for destruction?
ubiquitin polypeptides
35
What breaks the misfolded pr- down?
proteasomes
36
What is the main function of the endocytic pathway?
used to bring materials into the cell through endocytosis
37
How are solutes or particles brought into the cell during endocytosis?
they are enclosed in vesicles pinched from the plasma membrane and brought into the cell
38
What type of materials can some cells engulf during endosytosis?
some cells can engulf larger particles, including other cells
39
What happens to many materials after they are brought into the cell via endocytosis?
materials are delivered to lysosomes, where they are destroyed
40
What are 3 different types of endocytosis?
1. Phagocytosis
2. Clathrin-dependent endocytosis
3. Caveolae-dependent endocytosis
41
What is phagocytosis?
the use of cell surface protrusions to surround and engulf particles, forming vesicles called phagosomes
42
What is Clathrin-dependent endocytosis?
Membrane regions covered in clathrin, known as coated pits, contain receptors that specifically bind to macromolecules. When these pits pinch off from the membrane, they form clathrin-coated vesicles.
43
What is caveolae-dependent endocytosis?
involves membrane regions rich in cholesterol and caveolin. When these regions pinch off, they form caveolar vesicles.
44
TRUE OR FALSE: Caveolar vesicles do NOT deliver their contents to lysosomes
TRUE
45
What roles might caveolae-dependent endocytosis play in a cell?
- single transduction
- transport of small molecules and macromolecules
46
What are eukaryotic ribosomes made of and what is their size?
- composed of pr- and RNA
- size of 80S
47
Where can eukaryotic ribosomes be found in the cell?
attached to the ER or free in the cytoplasm
48
What is the fate of pr- made of ribosomes attached to the rough ER?
pr- are often secreted or inserted into the ER membrane as integral membrane proteins
49
What is the fate of pr- made by free ribosomes?
- Typically non-secretory and nonmembrane pr-
- can also be inserted into organelles
50
What are the key functions of mitochondria in a eukaryotic cell?
- site of the Tricarboxylic Acid Cycle (TCA)
- also where ATP is generated
51
ATP is generated by...
electron transport and phosphorylation
52
What unique features do mitochondria contain?
- ribosomes
- DNA (often in a closed circle)
- calcium phosphate granules
53
How are mitochondrial ribosomes and DNA similar to bacterial structures?
- mitochondrial ribosomes are similar in size to bacterial ribosomes
- DNA is often in closed circular form, also like bacterial DNA
54
How do mitochondria reproduce?
binary fission (similar to prokaryotic cells)
55
What is a key feature of the outer membrane of mitochondria?
the outer membrane contains porins, which are similar to those found in the outer membrane of gram-negative bacteria
56
What is the function of the highly folded inner membrane in mitochondria?
folded into structures called cristae
- contains enzymes and electron carriers necessary for electron transport and oxidative phosphorylation
57
What can be found in the mitochondrial matrix?
- ribosomes
- mitochondrial DNA
- large calcium phosphate granules
- enzymes for the tricarboxylic acid cycle and fatty acid catabolism
58
Where are the enzymes and electron carriers for oxidative phosphorylation located in the mitochondria?
- inner membrane of the mitochondria
59
What metabolic processes are supported by enzymes in the mitochondrial matrix?
1. Tricarboxylic acid (TCA) cycle
2. catabolism of fatty acids
60
What is the nucleus and what does it contain?
the nucleus is a membrane-bound organelle that contains the cell's genetic material
61
What is chromatin and where is it found?
Chromatin is a dense fibrous material found within the nucleus. It contains DNA and condenses to form chromosomes during cell division
62
What happens to chromatin during cell division?
it condenses to form chromosomes
63
What is the structure of the nuclear envelope and what is its function?
double membrane that surrounds the nucleus and is penetrated by nuclear pores
- function: allows the passage of materials between the nucleus and cytoplasm
64
How many nucleoli can be found in a nucleus?
1 or more nucleoli per nucleus
65
Is the NUCLEOLUS membrane-bound?
No, not membrane enclosed
66
What is the main function of the nucleolus?
important for ribosome synthesis
67
What specific roles does the nucleolus play in ribosome synthesis?
- directs the synthesis and processing of rRNA
- assembles rRNA with ribosomal pr- to form ribosomes
68
What is mitosis and what role does it play in the cell cycle?
mitosis is a component of the cell cycle that distributes DNA to 2 new nuclei
69
What is the ploidy (# of chromosomes) of progeny cells after mitosis compared to the parent cell?
same as the parent cell, so a diploid organism remains diploid after mitosis
70
What is meiosis and when does it occur?
meiosis is the sexual phase of the life cycle and involves a complex, two-stage process of nuclear division
71
What happens to the number of chromosomes during meiosis?
of chromosomes is reduced by 1/2, converting diploid cells to haploid cells
72
What is the significance of haploid cells produced by meiosis?
haploid cells can act as gametes, which are necessary for sexual reproduction
73
How do external cell coverings differ between prokaryotes and eukaryotes
- eukaryotes lack a cell wall
- eukaryotes often contain sterols, which enhances mechanical strength and reduces the need for a cell wall
74
What is an example of a sterol?
Cholesterol
75
What are some characteristics of external cell walls in eukaryotes?
most eukaryotes have an external cell wall that is rigid and have variable make-up
76
What are diatoms composed of
silica
77
TRUE OR FALSE: external cell walls of eukaryotes are chemically simpler than bacterial peptidoglycan
TRUE
78
What is a pellicle and where is it found?
supportive mechanism found below the plasma membrane in many protists
79
What are the characteristics of cilia?
- 5-20um long
- beat with 2 phases, functioning like oars for movement
80
How do flagella differ from cilia in structure and movement?
- 100-200um long
- move in an undulating fashion (contrast from oar-like motion)
81
What is "Molecular Unity?"
1. Same basic chemical composition
2. Same genetic code
3. Same metabolic processes
82
Does DNA synthesis happen BEFORE or AFTER the cells enter mitosis?
BEFORE
83
What are the 4 phases of mitosis?
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
84
What happens in prophase?
- chromatin condenses into chromosomes
- nucleolus disappears
85
What happens in metaphase?
- nuclear membrane dissoves @ beginning
- chromosomes become captured by microtubules
- chromosomes become aligned in centre of cell
86
What happens at the very beginning of metaphase?
nuclear membrane dissolves
87
What happens in anaphase?
- contraction of microtubules pulls apart
- chromosomes turn into sister chromosomes and move to opposite ends of cell
88
What happens in telophase?
- nucleus and nucleoli reform
- cytoplasm divides
- cleavage
