lect 1: cells Flashcards
cells vary enormously in _____________
appearance and function and size
-neuron use electrical signals
-second had paramecium and cilia
-third is cell in a snap dragon (very closely associated)
-fourth is macrophage (flat and spread out) looks for foreign invaders
-fifth is yeast
-even in one organ system, there can be many different cell types (200 different cell types in humans)
cells are fundamentally ___________________
similar inside
-building blocks: amino acids for proteins and nucleotides for genetic material
what are the basic commonalities of cells?
- Alive
-the cell is the smallest unit that is considered to be life - highly organized and complex
what are the basic properties of cells?
- alive
- highly organized and complex
- possess a genetic program (have information that can be passed to next generation, can be haploid (meiosis) or diploid)
- can produce more of themselves (replication)
- acquire and utilize energy (photosynthesis in plants, animals in ATP)
- carry out a variety of chemical reactions
- engage in mechanical activities (mobility and movement within cell like excreting waste)
- respond to stimuli (usually ends with changes in gene expression)
- perform self-regulation (feedback loops)
- evolve
how do cells evolve?
cells share many features
-common genetic code (DNA)
-plasma membrane
-ribosomes
tennent of modern biology
-last universal common ancestor
graph
-had very small prokaryotic cells billions of years ago
-folding of plasma membrane resulted in organelles
-mitochondria are due to symbiotic relationship
what are the two fundamentally different classes of cells?
-main differences: prokaryotes do not have nuclei, no membrane bound organelles and are smaller in size
-similarities: identical genetic language, common set of metabolic pathways, many common structural features
what is the venn diagramm of pros and euks?
-cytoplasm= everything inside the cell (cytosol is the fluid component)
what are the differences in genome size comparison?
eukaryotic genomes
-big
-alot of regulatory DNA
-defines program of multicellular development
-human body contains 200 different cell types
-mice and humans have the same number of genes (size doesn’t matter as much with genome)
what is the cell reproduction of eukaryotes?
mitosis
-complex process of cell division
-chromosome duplicated -> condense into compact structures
-separated by elaborate microtubule-containing apparatus (mitotic spindle)
-generates 2 identical daughter cells
what is the cell reproduction of prokaryotes?
-one copy of single chromosome
-reproduce via binary fission
-no process comparable to meiosis/gamete formation/true fertilization (ie. is sexual)
-conjugation (some): piece of DNA passed to another cell
-incorporation of foreign DNA from environment: microbial evolution
what is the locomotion of prokaryotes?
relatively simple:
flagellum
-thin protein filament
-protrudes from cell, rotates
-rotations exerts pressure against surrounding fluid-> propels cell
what is the locomotion of eukaryotes?
e.g. flagellum
-many protists, sperm cells
-structurally and functionally more complex than prokaryotes
what is archaea?
-archaea are actually more structurally similar to eukaryotes but look more like prokaryotes
-evolutionally related species
-live in extremely inhospitable environments (extremophiles)
-Phile=beloved
what are some types of extremophiles?
-methanogens: convert CO2+H2-> methane
-halophiles= salty environments, in dead sea, deep sea brine pools (5M MgCl2)
-acidophiles: pH as low as 0
-thermophile: high temperatures
-hyperthermophiles: ocean hypothermal vents (can live above 121 C, which we use to sterilize surgical instruments)
what are bacteria?
-live in every habitat on earth (e.g. rock layers)
includes smallest known cells
-mycoplasma: only prokaryote without cell wall, known for causing walking pneumonia
-cyanobacteria: cytoplasmic membranes-photosynthesis
what are types of eukaryotic cells?
protists
-complex eukaryote
similar to a whole organism
-sense the environment
-trap food
-expelling excess fluid
-evade predators
all within a single cell
what are multicellular eukaryotes (cell differentiation)?
-different cell types for different functions
-differentiation= formation of specialized cells
-number/arrangements of organelles relate to function/activity of cell
-various cell types still share common features (e.g. same organelles)
what are model organisms and why are they selected?
model organisms
-non-human species
-studied extensively
selected because
-properties of the organism
-easy to maintain and cheap
what are some examples of model organisms?
prokaryote
-E. coli
eukaryotes
-yeast
-Arabidopsis (plant)
-C. Elegan (worm)
-drosophila (fly)
-mus misculus (mouse)
-zebrafish
how are the sizes of cells and components measured?
-micrometers (1=10^-6m)
-nanometers (1=10^-9m)
cell size is limited by:
volume of cytoplasm that can be supported by:
-exchange of nutrients
-the genes in the nucleus
distance over which substances can efficiently travel through the cytoplasm via diffusion
what is the definition of archaeon?
microscopic organism that is a member of one of the two divisions of prokaryotes; often found in hostile environments such as hot springs or concentrated brine
what is the definition of bacterium?
microscopic organism that is a member of one of the two divisions of prokaryotes
-some species cause disease
-the term is sometimes used to refer to any prokaryotic microorganism, although the world of prokaryotes also includes archaea, which are only distantly related
what is the definition of a cell?
the basic unit from which a living organism is made; an aquaeous solution of chemicals, enclosed by a membrane, that has an ability to self-replicate
what is the definition of chloroplast?
specialized organelle in algae and plants that contains chlorophyll and serves as the site for photosynthesis
what is the definition of chromosome?
long, threadlike structure composed of DNA and proteins that carries the genetic information of an organism; becomes visible as a distinct entity when a plant or animal cell prepares to divide
what is the definition of cytoplasm?
contents of a cell that are contained within its plasma membrane but, in the case of eukaryotic cells, outside the nucleus
what is the definition of cytoskeleton
system of protein filaments in the cytoplasm of a eukaryotic cell that gives the cell shape and the capacity for directed movement
-its most abundant components are actin filaments, microtubules an intermediate filaments
what is the definition of cytosol?
contents of the main compartment of the cytoplasm, excluding membrane-enclosed organelles such as the endoplasmic reticulum and mitochondria
-also used to refer to the cell fraction remaining after membranes, cytoskeletal components, and other organelles have been removed
what is the definition of DNA?
double-stranded polynucleotide formed from two separate chains of covalently linked deoxyribonucleotides
-it serves the cell’s store of genetic information that is transmitted from generation to generation
what is the definition of electron microscope?
instrument that passes a beam of electrons through the specimen to reveal and magnify the structures of very small objects, such as organelles and large molecules
what is the definition of endoplasmic reticulum?
labyrinthine membrane-enclosed compartment in the cytoplasm of eukaryotic cells
what is the definition of eukaryote?
an organism whose cells have a distinct nucleus and cytoplasm
what is the definition of fluorescence microscope?
instrument used to visualize a specimen that has been labeled with a fluorescent dye’ sample are illuminated with a wavelength of light that excites the dye, causing it to fluoresce
what is the definition of evolution?
process of gradual modification and adaptation that occurs in living organisms over generations
what is the definition of genome?
the total genetic information carried by all chromosomes of a cell or organism
-in humans, the total number of nucleotide pairs in the 22 autosomes plus the X and Y chromosomes
what is the definition of golgi apparatus?
membrane-enclosed organelles in eukaryotic cells that modifies the proteins and lipids made in the endoplasmic reticulum and sort them for transport to different sites
what is the definition of homologous?
describes genes, chromosomes, or any structures that are similar because of their common evolutionary origin
-can also refer to similarities between protein sequences or nucleic acid sequences
what is the definition of a micrometer?
unit of length equal to one millionth (10^-6) of a meter or 10^-4 centimeter
what is the definition of a microscope?
instrument for viewing extremely small objects
-some use a focused beam of visible light and are used to examine cells and organelles
-others use a beam of electrons and can be used to examine objects as small as individual molecules
what is the definition of mitochondrion?
membrane-enclosed organelle, about the size of a bacterium, that carries out oxidative phosphorylation and produces most of the ATP in eukaryotic cells
what is the definition of model organisms?
a living thing selected for intensive study as a representative of a large group of species
-examples include the mouse (representing mammals), the yeast Saccharomyces cerevisiae (representing a unicellular eukaryote), and Escherichia coli (representing bacteria)
what is the definition of the nucleus?
in biology, refers to the prominent, rounded structure that contains the DNA of a eukaryotic cell
-in chemistry, refers to the dense, positively charged center of an atom
what is the definition of organelle?
a discrete structure or sub compartment of a eukaryotic cell that is specialized to carry out a particular function
-examples include mitochondria and the golgi apparatus
what is the definition of photosynthesis?
the process by which plants, algae and some bacteria use the energy of sunlight to drive the synthesis of organic molecules from carbon dioxide and water
what is the definition of plasma membrane?
the protein-containing lipid bilayer that surrounds a living cell
what is the definition of prokaryote?
major category of living cells distinguished by the absence of a nucleus’ includes the archaea and the eubacteria (commonly called bacteria)
what is the definition of a protein?
macromolecule build from amino acids that provides cells with their shape and structure and performs most of their activities
what is the definition of protozoan?
a free-living, nonphotosynthetic, single-celled, motile eukaryote
what is the definition of a ribosome?
large macromolecular complex, composed of RNAs and proteins, that translates a messenger RNA into a polypeptide chain
what is the definition of RNA (ribonucleic acid)
molecule produced by the transcription of DNA; usually single-stranded, it is a polynucleotide composed of covalently linked ribonucleotide subunits
-serves a variety of informational, structural, catalytic and regulatory functions in cells
