Ch. 1: The Cell Flashcards
What are the components of cell theory?
- all living things are composed of cells
- the cell is the basic functional unit of life
- cells arise only from preexisting cells
- cells contain genetic information (DNA) passed onto daughter cells
Viruses contian genetic information but cannot reproduce on their own
What is the difference between prokaryotes and eukaryotes?
prokaryotes do not have membrane bound organellse have have their genetic material in a single circular molecule of DNA in the nucleoid region
eukaryotes have membrane bound organelles, a nucleus, and form multicellular organisms
What is the organization and function of the nucleus?
and Nucleolus
the nucleus contians the genetic information and acts as the control center, it is surrounded by a double membrane (nuclear membrane) that contains nuclear pores that allow exchange between the cytosol and nucleus
Nucleolus is located in the nucleus and synthesizes ribosomal RNA
What is the organzation and function of mitrochondria?
- outer membrane seperates cytosol and inner mitochondrion
- inner membrane has many folds call cristae and contains molecules and enzymes for electron transport chain
- intermembrane space is between the membranes
- mitochondrial matrix is inside inner mitochondiral membrane
mitochondria have some of their own DNA so they can replicate independently of nucleus by binary fission
are able to release enzymes to start cell death
What is the function of lysosomes?
lysosomes contain hydrolytic enzymes that break down substrates
they work with endosomes which transport and package materials going in and out of the cell
the lysosomal membrane may open to release the enzymes for apoptosis – “autolysis”
What is the function of the endoplasmic reticulum?
Rough ER has ribosomes allowing for translation of proteins to be secreted into lumen.
Smooth ER is responsible for lipid synthesis and detoxification of some drugs.
ER is a series of interconnected and folded membranes.
What is the function of the golgi apparatus?
they are a stack of membrane bounds sacs that modify materials by adding carbs, phosphates, and sulfates or by adding signal sequences to direct delivery
the materials travel from the ER in vesicles to the golgi
What is the function of peroxisomes?
peroxisomes contain hydrogen peroxides to break down long fatty acids in B-oxidation and participate in phospholipid synthesis and the pentose phosphate pathway
What is the function of the cytoskeleton?
- cell structure and maintain shape
- conduit of transport of materials around the cell
Component of the Cytoskeleton
What are microfilaments?
Microfilaments are solid rods of actin that protect the cell by being resistant to compression and fracture.
They also play a role in cytokinesis and may use ATP in conjuction with myosin for muscle movement.
Component of the Cytoskeleton
What are microtubules?
Cilia? Flagella?
Microtubules are hollow tubulin proteins that provide pathways for motor proteins like kinesin and dynein.
They also form a 9+2 structure for cilia (projections from a cell to move materials along cell) and flagella (move the cell itself). 9 microtubules as an outer ring and 2 in the center?
Component of the Cytoskeleton
What are intermediate filaments?
They are responsible for cell-cell adhesion and maitenance of the cytoskeleton by helping anchor organells.
Ex. Keratin and desmin
What is the function of epithelial tissue?
Epithelial cells conver the body and line its cavities and protects agains pathogen invasion and desiccation. It may also be involved in absorption, secretion, and sensation. They are diverse and function depends on the organ. They are often polarized so that one side faces the lumen and the other blood vessels/structure.
- Basement membrane is the underlying layer of connective tissue.
- Simple epithelia have one layer of cells
- Stratified epithelia have multiple layers
- Pseudostratified epithelia are only one layer but appear to have multiple layers (differences in height)
Parenchyma - act in the function of the organ
Cuboidal (cube), columnar (column), or squamous (flat) shaped.
What is the function of connective tissue?
Connective tisue supports the body and provides the framework for the epithelial cells. Most cells secrete collagen and elastin to for the extracellular matrix.
Stroma - act to support the structure of the organ
Ex. Bone, cartilage, tendons, ligaments, adipose tissue, blood
Prokaryotes
Describe Archaea.
How are they similar to bacteria and eukaryotes?
- single celled organisims
- extremophiles that live in harsh environemnts and use chemical sources of energy
- singular circular chromosome that divides by binarry fission or budding
Like bacteria, archaea are single celled with no nucleus or membrane organells and have a single circular chromosome and repreoduce through binary fission. Like eukaryotes, archaea start translation with emthionine.
Describe Bacteria.
- contain a cell membrane and cytoplasm, some have flagella or fimbriae (like cilia)
- some have a mutualistic symbiosis or parasitic relationship with humans
What are the shapes of bacteria?
- cocci – spherical
- bacilli – rod shaped
- spirilli – spiral shaped
What are obligate aerobes?
bacteria that require oxygen to survive
What is the difference between obligate, facultative, and aerotolerant anaerobes?
Obligate anaerobes cannot survive in oxygen environments (cannot metabolise)
Facultative anaerobes can survive with or without oxygen (switch between metabolic processes)
Aerotolerant anaerobes cannot use oxygen for metabolism but can survive in oxygen environemnts
What is the difference between gram positive and gram negative bacteria?
Gram positive bacteria has a cell wall that absorbs a stain (turns purple) while gram negative bacteria have a cell wall that doesn’t absorb the violet stain (turns pink).
Gram positive bacteria have a thick cell wall with peptidoglycan and lipoteichoic acid.
Gram negative bacteria have a thin cell wall with peptidoglycan and an outer membrane with phospholipids and lipoplsaccharides.
the envelope of bacteria = cell wall + cell membrane
What are flagella and what is chemotaxis?
bacteria may have many flagella that move them towards food or away from immune cells
Chemotaxis is moving in response to chemical stimuli
What is binary fission?
asexual reproduction in prokaryotes
the circular chromosome attaches to the cell wall and replicates while the cell grows in size, the plasma membrane and cell wall will grow inwards to produce two cells
What is genetic recombination?
increases bacterial diversity since there are often plasmids in bacteria which carry genes (may be resistance genes or virulence factors)
An episome is a plasmid that integrates into the genome.
Recombination Process
What is transformation?
integration of foreign genetic material into the host geneome
Recombination Process
What is conjugation?
bacterial form of sexual reproduction
genetic material is transfered from one bacterium to another across a conjucation bridge
a plasmid can be transferred from F+ cells to F- cells
high frequency recombination may occur which is when the bridge breaks before all of the DNA is transferred
Recombination Process
What is transduction?
requires a vector - virus that transfers genetic material from one bacterium to another
What is a transposon?
a genetic element that is able to insert and remove itself from the genome
What is the growth curve of bacteria?
- lag phase - adapt to new conditions
- exponential phase - exponential growth
- stationary phase - reduced resources so the growth levels off
- death phase - resources deplete and death
What is the viral structure?
- genetic material that may be DNA/RNA, circular/linear, single/double stranded
- protein coat - capsid
- sometimes an envelope of lipids (makes it easier to kill since heat sensitive)
What is a bacteriophage?
viruses that specifically target bacteria and inject their genetic material and leave the remaining structrue outside the cell
Tail sheath: syringe-like that injects genetic material
Tail fibers: help bacteriophage recognize and connect to the correct host cell
In single stranded RNA viruses, what does it mean to be positive or negative sense?
Positive sense: genome may be directly translated to functional proteins by ribosomes of the hose cell
Negative sense: RNA strand acts as a template for synthesis o complementary strand (must carry RNA replicase)
What are retroviruses?
enveloped, single-stranded RNA genome tat uses reverse transcriptase to create a complementary DNA strand that amy be integrated into the genome
Describe the viral life cycle?
- viruses infect cells by attaching to receptors
- enter by fusing with plasma membrane or endocytosis or by injecting genome
- viruse reprroduces by replicating and tranlating genetic material using the host
- viral progeny is released
Compare lytic and lysogenic cycles?
lytic cycle causes a massive number of new virions until the cell lyses
lysogenic cycle causes the virus to integrate into the host genome and reproduce along with the cell
What is a prion?
an infection protein that causes disease by midsfolding other protiens
usually changes alpha helices to beta sheets
What is a viroid?
small pathogen that has a very short circular single-stranded RNA that infects plants, they turn off genes that causes cell death
