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