Cells Flashcards
1
Q
What are the most abundant and versatile macromolecules?
A
Proteins
2
Q
What is the structure of an amino acid?
A
It has an amino group on one end and a carbonyl group on the other as well as a R group
3
Q
What is an R group?
A
A side chain attached to amino acids which determine its chemical and physical properties
4
Q
What links amino acids in proteins together? What does this bond form between?
A
Peptide bonds, forms between the carbonyl group of one amino acid and the amino group of another
5
Q
What are the carbonyl and amino ends of an amino acid sequence called?
A
N-terminus and C-terminus
6
Q
What is the primary structure of a protein? What bonds are used?
A
Amino acid sequence, uses peptide bonds
7
Q
What are the types of secondary structures? What type of bond is used?
A
Alpha-helix and beta-pleated sheet, hydrogen bonds
8
Q
Do proteins need to contain only one type of secondary structure?
A
No it can be a mix of both
9
Q
What is tertiary structure? What bonds are used?
A
Folding due to R-group interactions, can be ionic, disulfide, hydrogen, or van der waals bonds
10
Q
What determines the type of bond in tertiary structure?
A
The type of R-group
11
Q
What is quaternary structure?
A
Structure involving more than one polypeptide
12
Q
A protein made up of more than one polypeptide contains which structure(s)?
A
Primary, secondary, tertiary, and quaternary
13
Q
What helps make sure that proteins are properly folded?
A
Chaperone proteins which ensure they fold properly and other proteins which eliminate improperly folded proteins
14
Q
What are some of the primary functions of carbohydrates in cells?
A
Energy storage, cell identity, structure, and building blocks
15
Q
Lipid structure is diverse but they are usually?
A
Hydrophobic/non-polar
16
Q
What is the basic unit of a nucleic acid called?
A
Nucleotide
17
Q
What are nucleotides composed of?
A
A nitrogenous base, a pentose sugar, and a phosphate group
18
Q
What are the similarities and differences between DNA and RNA?
A
- both made of nucleotides
- both contain 4 nitrogenous bases
- DNA has thymine and rna has uracil
- dna is double stranded rna is single stranded
- dna can self replicate rna cannot
19
Q
What is the flow of information in cells?
A
DNA codes for RNA which codes for proteins
20
Q
What is transcription? What facilitates this process?
A
Turning DNA into RNA, rna polyermerase
21
Q
What is translation? What facilitates this process?
A
Turning RNA into proteins, ribosomes
22
Q
What are three things that are true of all cells concerning energy and metabolism?
A
- All cells need source of carbon and energy
- All cells use energy to build macromolecules and carry out processes of life
- All cells use atp as the major energy carrier
23
Q
What is the difference between autotrophs and heterotrophs?
A
Autotrophs make their own energy and heterotrophs get it from other organisms
24
Q
What is the difference between phototrophs, chemoorganotrophs, and chemolithotrophs?
A
Phototrophs get energy from sunlight, chemoorganotrophs get energy from organic molecules, and chemolithotrophs get energy from inorganic kolecules
25
Which domain of organisms have more diversity in how they obtain energy?
Prokaryotes
26
What are some common structural features that prokaryotic cells share?
- no nucleus
- ribosomes
- cytoplasm
- cell membrane
- cell wall
- glycocalyx
- flagella/pili
27
What is true about bacterial DNA?
Most have a single, circular DNA molecule and it is contained in the nucleoid
28
What are plasmids?
Extra-chromosomal pieces of DNA that carry non-essential genes
29
What is true of plasmid structure and function?
Small circular DNA molecules, extra genes that can have beneficial or detrimental affects, replicate independently of chromosomal DNA, and bacteria may lose plasmids when they replicate
30
What protein is involved in binary fission? What is its purpose?
FtsZ, forms a ring in center of bacteria and pinches cytoplasm until it seperates
31
What protein is used in rod shaped cells specifically? What is the purpose?
MreB proteins, maintains the rod shape
32
What are ribosomes?
Macromolecular machines for protein synthesis made up of protein and RNA
33
What is the cytoskeleton?
Proteins involved in support, shape, and cell divison
34
What are the functions of the bacterial cell membrane?
Boundary of the cell, metabolism, photosynthetic bacteria also often have internal membrane which derives from the plasma membrane
35
Bacteria cell walls can be? What is the difference?
Gram positive bacteria (single, thick peptidoglycan layer) or gram negative bacteria (thin peptidoglycan layer surrounded by outer membrane)
36
Which type of cell wall is more susceptible to an antibiotic which targets the cell wall? Why?
Gram positive cell wall, not protected by outer membrane
37
What can weakening the cell wall lead to? What can cause this?
Cell rupture and death, antibiotics that target peptidoglycan synthesis and lysozyme
38
What is the glycocalyx?
A structure outside the cell wall of some bacteria, sometimes called capsule or slime layer
39
What is the purpose of the glycocalyx?
Protects bacteria from extreme temperatures, desiccation, antibiotics, viruses, antibodies
40
What are flagella?
Allows for movement
41
What are fimbriae?
Short, hair like structure that is used for attaching to surfaces or other cells, not used for mobility
42
What are pili?
Short structure used to make initial contact to bring bacteria together to transfer genetic material (conjugation)
43
How are archaea similar to bacteria?
Many are found in extreme environments, diverse metabolisms, prokaryotes, nucleoid, circular chromosome, ribosomes, cytoskeleton, most have cell walls, some have glycocalyx, flagella, and fimbria like structures
44
What part of archaea is more similar to eukaryotic cells than bacteria?
The information system (ribosomal structure, and the aspects of translation and transcription)
45
How are archaea structurally different from bacteria and eukaryotes?
- Have a unique flagella, cell wall, glycocalyx, fimbria-like structures, cytoskeleton, membrane lipids
46
What are the major differences between eukaryotic cells and bacteria/archaea?
Larger than prokaryotes, distinct nucleus surrounded by nuclear envelope, membrane bound organelles (endomembrane system)
47
What are similarities and differences between plant and animal cells?
- both have nucleus, cell membrane, mitochondria, ER, ribosomes, golgi etc
- plant cells have chloroplasts and a cell wall and animal cells don’t
- animal cells have lysosomes and centrioles and plant cells don’t
- in plant cells vacuoles are large, there is only one, and helps maintain water balance and in animal cells there are many small vacuoles and help store waste
48
What is the nucleus/nuclear membrane and what are the functions?
Membrane enclosed organelle that contains genetic information and regulates activities of cell, acts as barrier and seperates the nucleus contents from the cytoplasm
49
What is the ER? Function?
Membrane system formed from a series of flattened sacs and is important for protein synthesis (rough er) and transport, lipid and steroid synthesis (smooth er) and calcium storage
50
What is the Golgi apparatus and it’s function?
System of flattened sacs called cisternae, Helps transport, modify, and package proteins and lipids into vesicles
51
What are lysosomes and what is its function? Where do they originate?
Breakdown of macromolecules including worn out organelles, responding against foreign substances (bacteria, viruses) originate from golgi
52
What are vacuoles and it’s function?
In animal cells, they help contain waste products and in plant cells they help maintain water balacne
53
What are peroxisomes and their function?
They help contain oxidative reactions and play important roles in metabolism and signaling
54
What is the role of mitochondria?
Generate most of the energy the cell uses by generating ATP
55
What is the role of the chloroplast?
Plant cell organelles that convert light energy into usable chemical energy
56
What is role of cytoskeleton?
Structure that helps maintain cells shape and internal organization
57
What is role of plasma membrane/cell wall?
Cell wall proves strength and protection and mechanical and osmotic stress and membrane keeps unwanted substances out of cell
58
What is the endomembrane system?
Collection of interrelated internal membranous sacs that divide the cell into compartments called organelles
59
What organelles are part of the endomembrane system?
Nuclear membrane, SER and RER, Golgi apparatus, vesicles, lysosomes, vacuoles
60
What are some of the functions of the endomembrane system?
1. Synthesis, modification, transport, and secretion of proteins
2. Synthesis of lipids and detoxification of toxins
3. Transportation and breakdown of large bio molecule containing particles
61
What is the hypothesis for the evolution of the endomembrane system?
All of the related membranes in this system were derived from the plasma membrane
62
What is the nuclear membrane made up of?
Two phospholipid bilayers
63
What is the nuclear lamina and what does it do?
Is a mesh like structure that provides structural support to the nucleus and protects the dna
64
How does nuclear DNA usually exist?
Chromatin
65
What is euchromatin? How can you tell where it is? What does it mean?
Loosely packed dna, lighter regions, genes are active and transcription is occuring
66
What is heterochromatin? How can you tell? What does it mean? Where does this usually occur?
Densely packed dna, darker regions, genes are inactive and transcription is not occurring, parts of body where certain genes are not needed
67
What is the nucleolus?
Non membrane bound structure inside the nucleus composed of proteins and nucleic acids
68
What is the nucleolus the site of?
rRNA synthesis, and ribosomal subunit assembly
69
How is nuclear transport regulated? Where are these structures located?
By nuclear pores which are embedded in nuclear envelope
70
What is a nuclear pore complex composed of? What does this control?
Different proteins, the traffic between the cytoplasm and the nucleus
71
Which signal is required for nuclear import? Export?
NLS, NES
72
What are nuclear localization and nuclear export signals?
A sequence of amino acids which “tag” something for import or export
73
Does nuclear transport require energy?
Yes, proteins contain GTP and phosphorylate into GDP
74
What items need to enter and exit the nucleus?
- rRNA needs to exit
- mRNA needs to enter
- ATP
- proteins
- nucleic acids
75
What is insulin?
Protein that regulates blood sugar levels
76
How does the cell increase the number of insulin proteins made from mRNA?
Recruit more ribosomes to the strand
77
Steps in insulin synthesis?
Starts as preproinsulin, loses signal sequences and is now called proinsulin, loses peptide chain c and is now insulin
78
What role does smooth ER have in liver? Reproductive organs?
Breaks down drugs, poisons and toxic byproducts, makes steroid sex hormones
79
What are the 5 steps in targeting protein to the ER (signal hypothesis)
1. ER signal sequence is synthesized
2. Signal sequence binds to signal recognition particle and stops synthesis
3. SRP binds to receptor in er membrane
4. SRP is released, synthesis continues, protein enters er through the translocon
5. Signal sequence is removed and protein synthesis proceeds to completion
80
Why does protein synthesis temporarily stop when SRP receptor binds?
So the unfinished protein does not get released into cytoplasm before complete and folding occurs
81
Where do bonds begin forming in ER synthesized proteins? How?
The ER lumen, chaperone proteins
82
How do proteins go from one organelle to another?
Exocytosis: protein leaves er and use vesicles to transport to another organelle
83
Why can vesicles leave and join ER and Golgi easily? Why is this true?
Same phospholipid bilayer, theory of the evolution of the endomembrane system
84
How do vesicles move around the cell? Why? How?
An unorganized manner from multiple organelles at once, more efficient for the cell, regulated by proteins
85
What do vesicles connect the ER, Golgi and plasma membrane to?
Er to Golgi, Golgi to membrane, membrane to lysosomes and peroxisomes
86
What side do proteins from the RER enter the Golgi? Which organelle do these sides face?
Enter from cis face and leave via trans face, cis faces nucleus trans faces plasma membrane
87
How are proteins modified in the Golgi?
Functional groups may be added to assist with protein function, sugars or lipids could be added, amino acids could be removed
88
When vesicles fuse with the plasma membrane does the surface area increase? Why?
No, because endocytosis which is the reverse process counter acts it and creates balance
89
What is the difference between exocytosis and endocytosis?
Exocytosis moves molecules out of the cell and endocytosis brings molecules into the cell
90
What are the three pathways leading to lysosomes?
1. Receptor mediated endocytosis
2. Phagocytosis
3. Autophagy
91
How does receptor mediated endocytosis work?
Receptors bind to macromolecules outside of the cell and the plasma membrane pinches in to form a vesicle that delivers it to early endoscope one which is acidified and eventually turns into a lysosome
92
How does phagocytosis work?
Brings smaller cell or food particles into the cell making a phagosome which is delivered to lysosome which fuse together and the lysosome digests the contents
93
How does autophagy work?
Encloses damaged organelle forming an autophagosome that is delivered to lysosome and digested
94
What do lysosomes release into cytosol?
Small molecules
95
What is the theory of endosymbiosis?
Mitochondria developed from ingested aerobic prokaryotes (alpha proteobacteria) and chloroplasts developed from injected Cyanobacteria
96
What are the proposed initial steps in mitochondrial evolution?
Bacteria was engulfed and survived forming a symbiotic relation and eventually become inseparable
97
What is the evidence for the origin of mitochondria and chloroplasts?
- same shape and size of bacteria
- contain own dna (shorter than nuclear dna and circular)
- contain own transcription and translation machinery
- rRNA sequence like bacteria
- multiply by binary fission
- cell cannot make either
- internal membrane system contains key metabolic molecules/processes
- double membrane from when it got engulfed
98
Could mitochondria and chloroplasts still survive on their own?
No because they are too dependent on rest of cell now
99
What are the three major classes of cytoskeletal filaments?
Actin filaments (microfilaments)
Intermediate filaments
Microtubules
100
Which cytoskeletal filaments have polarity?
Microfilaments and microtubules
101
What is polymerization in terms of filaments?
Assembly of monomers to extend length of filament, added to + end
102
What is depolymerization in terms of filaments?
Disassembly of the filament, monomers removed from + end
103
What is the function of actin (microfilaments)? Where are they located?
Dynamic of polar filaments, help with cell shape/structure and motility, they rest under the plasma membrane
104
How does Actin and polymerization facilitate amoeboid movement?
Actin arranges itself and polymerize along the leading edge(direction of movement) of the moving cell
105
What is the types of intermediate filaments? What are their function? What do they form?
Types made up of different proteins (lamins, keratin)
Less dynamic and non polar
Provide mechanical strength and maintain cell shape, and nuclear position shape and organization
Hair nails etc
106
What are microtubules? What are their function?
Polar and dynamic
Attach to centrosome (centrosome is negative end and other end is positive)
Can grow and shrink (depolymerize causes shrinking and polymerize grows)
Helps with cell shape and structure, cell movement and cell division
107
What does cytoskeletal movement require?
The activity of motor molecules that associate with actin and microtubules
108
What are the major motor molecules and what do they associate with?
Myosin, actin
Kinesin and dyenin, microtubules
109
What direction does myosin move?
Growing positive end of actin
110
What do actin and myosin work together to cause? How?
Muscle contractions, myosin are between each microfilament and as they move the muscle contracts
111
How does actin and myosin help during cytokinesis?
Arrange themselves along the sides of the membrane and allow it to pinch off
112
What direction does kinesin move? What drives it? What does it carry?
From center of cell to outside of cell (+), atp hydrolysis, positions organelles and carries vesicles
113
What direction does dyenin move? What does it transport? What else is it involved in?
From the membrane to center of cell (-), transports vesicles and organelles, involved with cilia and flagella movement
114
What are flagella associated with? How do they move? What are they used for?
Associated with microtubules and dyenin, make whip/oar like motions, used for movement
115
What are cilia associated with? What are they used for? How do they move?
Microtubules and dyenin, sweep out things to prevent infection and move fluids over cell surface, back and forth oar like motion
116
What is true about bacterial and eukaryotic flagella?
Have the same function but both evolved independently
117
Why are eukaryotic cells usually larger?
They have many different compartments, large area of internal membranes(endomembrane), specialized structures with specialized functions(mitochondria)
118
What is the best surface area to volume ratio? Why?
6:1, most efficient for transporting materials across the cell membrane
119
How do lysosomes maintain pH?
Proton pumps
