chapter 7: cell evolution, prokaryotes, eukaryotes Flashcards
LUCA
last universal common ancestor; first cell on earth, ancestor of all biological life on planet
stages of chemical evolution
1) inorganic molecules build complex molecules
2) complex molecules create RNA replicators and lipid structures
3) life
stage 1: building complex molecules
white smoker hydrothermal vents on early earth contained minerals, sulfur, simple chemical compounds, and an energy gradient
stage 2a: the rise of replicators
for anything to be a replicator, it must:
1) contain information that leads to its replication
2) cause itself to replicate based on informations interaction with environment
RNA- world hypothesis
proposes RNA was likely the molecular replicator responsible for kick starting life on earth; RNA’s can catalyze chemical reactions (ribozymes)
stage 2b: formation of phospholipid bubbles
phospholipid bilayers keep internal environment separate from outside world - beneficial bc it’s easier to sustain life
cell theory
- all living things are composed of 1 or more cells
- cells are the basic units of structure and function in living things
- new cells are produced from pre existing cells
common features of all cells on Earth
cell membrane, cytoplasm, genome of DNA, ribosomes
features of prokaryotes
cell wall, some have additional outer plasma membrane, some have slimy capsule of polysaccharide, flagellum & fimbriae, can exist as free living single cells or in aggregates
flagellum
whip like protein complex that allows prokaryotes to move
fimbriae
hair like projections that allow prokaryotes stick to surfaces
endosymbiosis
mutually beneficial relationship between two organisms where one lives in the body of the other -single celled organelles engulfed and kept during eukaryotic evolution
3 things plant cells have that animal cells do not
- cell wall
- chloroplasts
- large central vacuole
prokaryote DNA
single circular super coiled chromosome in a region called the nucleoid
how do bacteria reproduce?
they transfer plasmids to each other
functions of cytoskeleton
- supports and maintains cell shape
- track for organelle and vesicle movement
- anchors cell and organelles
- make up cilia and flagella
structural features of cytoskeleton
- long spindle like protein fibers
- dynamic and in flux or stable
where do transmembrane proteins anchor to?
structural proteins
structures of the endomembrane system
1) nucleus
2) endoplasmic reticulum
3) golgi apparatus
4) vesicles
endomembrane system process
1) in nucleus, DNA is stores and RNA copies of genes are made
2) in ER, proteins and lipids are synthesized; proteins are folded and checked
3) in the golgi, proteins are modified, packaged, and put in vesicles for transport and sent to where they function
4) vesicles take proteins to the external cellular membrane to the final destination of protein function or vesicles mature into their own organelles
where are ribosomes made?
nucleolus
nuclear envelope
two membranes perforated by nuclear pores that regulate movement of substances; only allows certain things in and out; molecules need a specific series of amino acids to enter
smooth ER
lipid synthesis and lipid modification; stores calcium ions for cell signaling
cis golgi
receives vesicles from ER
trans golgi
sends vesicles of proteins to where they function
how do vesicles know where to go?
they use motor proteins on the cytoskeleton
what organelles are matured vesicles?
lysosomes and peroxisomes
lysosomes
- break down unwanted substances (bacteria and worn out organelles)
- hydrolyzes nucleic acids, carbs, proteins, and lipids
why is it not a good idea for lysosomal enzymes to not work in the cytosol of a cell?
it will disassemble polymers needed for cell to work
central vacuole
- plant and fungi cells
- store ions and toxic compounds
- fluid filled
- store pigments in flowers
- provide structure for plant
isotonic
equilibrium
hypertonic
water leaving; cell shrivels; salt water
hypotonic
water entering; cell swells; distilled water
what is the extracellular matrix made up of
a web of proteins; composition and layering depend on purpose
plasma membranes in prokaryotes
- provide a location for molecules that harvest energy from light
- allow for multiple distinct biochemical regions to drive energy transfer reactions
chloroplasts function
- site of photosynthesis
chloroplasts structure
- 3 plasma membranes
- outer membrane, inner membrane, thylakoid membrane
(thylakoids create granum)
mitochondria function
site of chemical reactions of cellular respiration that supply most of the cellular energy
mitochondria structure
- two membranes - inner and outer
- creates 3 spaces for molecules to interact (matrix, intermembrane space, cytoplasm) (this is how ATP is made)
peroxisomes
- carry out redox reactions
- small vesicle organelle (similar to lysosome)
- detoxifies cell of lipids and alcohols
nuclear pore complex
gates entry and exit into the nucleus
nuclear localizing signal
specific series of amino acids required for nucleus entry
nuclear exit signal
different specific series of amino acids required for nucleus exit
cytosolic ribosomes
cytosol, chloroplasts, mitochondria, peroxisomes, nucleus
RER ribosomes
outside of cell, cells surface, cell membrane, lysosomes, back to ER
endocytosis
receptors with a signal, membrane proteins that need to be recycled, molecules brought into cytoplasm
exocytosis
molecules sent to extracellular space, membrane associated proteins distributed to plasma membrane
phagocytosis
engulfs larger particles of entire cells
pinocytosis
small dissolved substances or fluids
phagocytosis pathway to lysosome
entire cells are brought into the cell and disassembled by the lysosome
autophagy pathway to lysosome
worn out organelles are destroyed in the lysosome
what motor proteins move on microtubules
kinesin and dynein
what else do motor proteins move
cilia and flagella
how do binding partners of motor proteins create movement
rearranging bonds
