Ch 1 - The Cell Flashcards
1
Q
What are the 4 fundamental tenets of the cell theory?
A
- all living things are composed of cells
- the cell is the basic functional unit of life
- cells arise only from pre-existing cells
- cells carry genetic information in the form of deoxyribonucleic acid (DNA) and this genetic material is passed on from parent to daughter cell
2
Q
What is the main difference between prokaryotic and eukaryotic cells?
A
- pro: always single-celled with no nucleus
- eu: can be unicellular or multicellular and contain a true nucleus enclosed in a membrane
3
Q
Where are organelles found?
A
- each cell has a membrane enclosing a semifluid cytosol (cytoplasm) where organelles are suspended
4
Q
What does the membrane in eukaryotic cells consist of and why is it unique?
A
- consist of a phospholipid bilayer
- its surfaces are hydrophilic, electrostatically interacting with the aqueous environment inside and outside the cell, while its inner portion is hydrophobic, which helps to provide a highly selective barrier between the interior of the cell and the external environment
5
Q
What is the nucleus?
A
- control center of the cell
- contains all the genetic material necessary for replication of the cell
- site of transcription
6
Q
What surrounds the nucleus?
A
- nuclear membrane (envelope)
- a double membrane that maintains a nuclear environment separate and distinct from the cytoplasm
7
Q
What are nuclear pores?
A
- in the nuclear membrane that allows selective 2-way exchange of material between the cytoplasm and the nucleus
8
Q
Genes?
A
coding region in genetic material (DNA)
9
Q
Histones?
A
- organizing proteins that linear DNA wounds around
10
Q
Chromosomes?
A
after linear DNA wounds around histones, they then further wind into linear strands = chromosomes
11
Q
Nucleoulus?
A
- where rRNA is synthesized
- takes up approximately 25% of the volume of the entire nucleus and can often be identified as a darker spot in the nucleus
12
Q
What is Mitochondria?
A
- powerhouse of the cell due to their important metabolic function
- semiautonomous: contain some of their own genes and replicate independently of the nucleus via binary fission
- capable of killing the cell by releasing enzymes from the ETC
13
Q
What is the difference between the outer and inner membrane of the mitochondria?
A
- outer: serves as a barrier between the cytosol and the inner environment of the mitochondrion
- inner: (arranged into numerous folding - cristae - that increase surface area for ETC enzymes) contains the molecules and enzymes of the electron transport chain
- intermembrane space: space between the membranes containing the mitochondrial matrix
14
Q
What is extranuclear inheritance (cytoplasmic)?
A
- the transmission of genetic material independent of the nucleus
15
Q
Apoptosis?
A
programmed cell death
16
Q
Lysosomes?
A
- membrane-bound structure containing hydrolytic enzymes that are capable of breaking down substances ingested by endocytosis and cellular waste products
- surrounded by a single membrane
17
Q
Autolysis?
A
- release of hydrolytic enzymes transported by endosomes/lysosomes leading to degradation of cellular components
18
Q
Endoplasmic reticulum?
A
- a series of interconnected membranes that are actually contiguous with the nuclear envelope
- double membrane is folded into numerous invaginations, creating complex structures with a central lumen
19
Q
What are the 2 types of ER?
A
- rough: with ribosomes, synthesizes protein destined for secretion
- smooth: lacks ribosomes and is utilized primarily for lipid synthesis and the detoxification
20
Q
Golgi Apparatus?
A
- consists of stacked membrane-bound sacs in which cellular products can be modified, packaged, and directed to specific cellular locations
21
Q
Perioxisomes?
A
- contain hydrogen peroxide
- breaks down long chain fatty acids via beta-oxidation
- synthesize lipids
- contribute to pentose phosphate pathway
22
Q
Cytoskeleton?
A
- provides structure to the cell and helps it to maintain its shape
- provides transport pathways for molecules within the cell
- 3 parts: microfilaments, microtubules, intermediate filaments
23
Q
Microfilaments?
A
- composed of actin.
- provide structural protection for the cell and can cause muscle contraction through interactions with myosin
- help form the cleavage furrow during cytokinesis in mitosis
24
Q
Microtubules?
A
- composed of tubulin
- create pathways for motor proteins like kinesin and dynein to carry vesicles
- contribute to the structure of cilia and flagella
25
What is the difference between cilia and flagella?
- cilia: projections from a cell that are primarily involved in the movement of materials along the surface of the cell
- flagella: structures involved in the movement of the cell itself
- they share the same structure: organized into 9 pairs of microtubules in a ring with 2 microtubules at the center (9+2 structure)
26
Why are viruses not considered living things?
they are acellular, cannot reproduce without the assistance of a host cell, and may use RNA as their genetic material
27
Cytosol?
suspends the organelles and allows diffusion of molecules throughout the cell
28
Centrioles?
- found in centrosomes and are involved in microtubules organization in the mitotic spindle
29
Intermediate filaments?
- involved in cell-cell adhesion and maintenance of the integrity of the cytoskeleton
- help anchor organelles
- keratin, desmin, vimentin, lamins
30
Epithelial tissue?
- cover the body and line its cavities, protecting against pathogen invasion and desiccation
- some absorb or secrete substances or participate in sensation
31
Parenchyma?
- the functional parts of the organ
| - in most organs, formed by epithelial cells
32
How can epithelial cells be polarized?
with one side facing a lumen or the outside world and the other side facing blood vessels and structural cells
33
How are epithelia classified by the number of layers?
- simple: have one layer
- stratified: have many layers
- pseuodostratified: appear to have multiple layers due to differences in cell heights, but actually only have one layer
34
How are epithelia classified by the shapes of the cells?
- cubodial: cube-shaped
- columnar: long and narrow
- squamous: flat and scalelike
35
Connective tissue?
- support the body and provide framework for epithelial cells
- in most organs, CT forms the stroma or support structure by secreting materials to form an ECM
- bone, cartilage, tendons, ligaments, adipose tissue, and blood
36
What are the 3 overarching domains of life?
- archae: extremophiles, living in harsh environments and often use chemical sources of energy rather than light (similarities to both eukaryotes - start translation with methionine, RNA polymerases, histones- and bacteria - single circular chromosome, divide by binary fission/budding
- bacteria: many similar structures to eukaryotes and have complex relationships with humans, including mutualistic symbiosis (good bacteria) and pathogenesis
- eukaryoa: only non-prokaryotic domain
37
How can bacteria be classified by shape?
- cocci: spherical
- bacilli: rod shaped
- spirilli: spiral shaped
38
How can be bacteria be classified based on metabolic processes?
- obligate aerobes: require oxygen for metabolism
- obligate anaerobes: cannot survive in oxygen-containing environments and can only carry out anaerobic metabolism
- facultative anaerobes: can survive in environments with or w/o oxygen and will toggle between metabolic processes based on the environment
- aerotolerant anaerobes: cannot use oxygen for metabolism, but can survive in an oxygen-containing environment
39
What forms the envelope in bacteria?
- the cell wall and cell membrane
| - together, they control the movement of solutes in and out of the cell
40
How can gram staining with a crystal violet stain followed by a counter stain with safranin classify bacteria?
- gram positive: turns purple, have thick cell wall composed of peptidoglycan and lipoteichoic acid
- gram negative: turns pink-red, thin cell wall composed of potidoglycamn and an outer membrane containing phospholipids and lipopolysaccharides
41
What is chemotaxis and what role does it play with bacteria flagella?
- bacteria may have 1, 2, or many flagella that generate propulsion to move the bacterium toward food or away from immune cells
- moving in response to chemical stimuli = chemotaxis
- bacterial flagella contain a filament composed ot flagellin, a basal body that anchors and rotates the flagellum and a hook that connects the 2
42
How to prokaryotes carry out the electron transport chain?
using the cell membrane
43
How do ribososmes compare between eukaryotes and prokaryotes?
prokaryotic ribosomes are smaller than eukaryotic (30s and 50s, rather than 40s, and 60s)
44
Binary fission?
- how prokaryotes multiply
- chromosomes replicate while the cell grows in size until the cell wall begins to grow inward along the midline of the cell and divides into 2 identical daughter cells
45
What can plasmids carry and what are their characteristics?
- extrachromosomal material can be carried in plasmids
- may contain Abx resistance genes or virulence factors
- can integrate into the genome = episomes
46
Transformation?
occurs when genetic material from the surroundings is taken up by a cell, which can incorporate this material into its genome
47
Conjugation?
- the transfer of genetic material from one bacterium to another across a conjugation bridge
- a plasmid can be transferred from F+ cell to F- cells, or a portion of the genome can be transferred from an Hfr cell to a recipient
48
Transduction?
the transfer of genetic material from one bacterium to another via a bacteriophage vector
49
Transposons?
genetic elements that can insert into or remove themselves from the genome
50
What is the pattern of bacterial growth?
- lag phase: the bacteria adapt to new local conditions
- exponential (log) phase: growth then increases exponentially
- stationary phase: as resources reduce, growth levels off
- death phase: as resources deplete
51
Capsid?
- viruses contain genetic material, a protein coat (caspid), and sometimes lipid-containing envelope
52
Why are viruses considered intracellular parasites?
they cannot survive and replicate outside of a host cell
53
Virions?
individual virus particle
54
What are bacteriophages and their components?
- viruses that target bacteria
- contain a tail sheath: injects the genetic material into a bacterium
- contain a tail fiber: allow the bacteriophage to attach to the host cell
55
What are the different compositions of viral genomes made of?
- DNA or RNA and may be single or double stranded
- sing stranded RNA virus may be positive sense (can be translated by host) or negative sense (require complementary strand to be synthesized by RNA replicase before translation)
- retroviruses have single stranded RNA genome that a complemntary DNA strand is made using RT
56
How do viruses infect cells?
by attaching to specific receptors, and can then enter the cell by fusing with the plasma membrane, being brought in by endocytosis or injecting their genome into the cell
57
How do viruses reproduce?
by replicating and translating genetic material using the host cells ribosomes, tRNA, amino acids, and enzymes
58
How are viral progeny released?
through cell death, lysis, or extrusion
59
What are the 2 life cycles for bacteriophages?
- lytic: the bacteriophgage produces massive numbers of new virions until the cells lyse (virulent)
- lysogenic: the virus integrates into the host genome as a provirus or prophage, which can then reproduce along with the cell; provirus can remain in the genome indefinitely, or may leave the genome in response to a stimulus and enter the lytic cycle
60
Prions?
- infections proteins that trigger misfolding of other proteins, usually converting alpha-helical structure to a beta-pleated sheet
- this decreases the solubility of the protein and increases its resistance to degradation
61
Viroids?
- plant pathogens that are small circles of complementary RNA that can turn off genes, resulting in metabolic and structural changes and potentially cell death
