cells Flashcards
characteristics of eukaryotic cells?
fungi, animals, humans, plants. DNA in a nucleus that is bounded by a double membrane. membrane-bound organelles. cytoplasm - region between the plasma membrane and nucleus. eukaryotic cells are generally larger than prokaryotes.
characteristics of prokaryote cells?
prokaryotes are bacteria. no nucleus. DNA in an unbound region called the nucleoid. no membrane bound by organelles. cytoplasm bound by the plasma membrane.
plasma membrane?
phospholipid and protein cell boundary (integrated proteins). selectively permeable barrier which permits certain materials to enter and certain to exit. transport proteins are often responsible for controlling passage across cellular membranes. in the fluid mosaic model, the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.
cytoplasm?
water, biochemical, solutes and organelles that fill the majority of the cell and support.
ribosomes?
organelle of RNA and protein that makes protein. protein factories. ribosomes are complexes made of ribosomal RNA and protein. ribosomes carry out protein synthesis in the cytosol (free ribosome) and on the outside of the ER or the nuclear envelope.
DNA?
genetic material encoding proteins’ structures.
differences between prokaryotes and eukaryotes?
prokaryotes have no nucleus and have no membrane bound organelles, whereas eukaryotes have membrane bound organelles. prokaryotes have 2 RNA in the large subunit and 1 in its small, giving it a smaller overall size. eukaryotes have 3 RNA molecules in the upper sub-unit, giving a greater all size, same in the sub-unit.
core four similarities between prokaryotes and eukaryotes?
DNA, ribosomes, plasma membrane, cytoplasm.
what is cell theory?
repeated microscopic observations of many organisms. cells are the basic unit of life. cells usually arrise from pre existing cells.
who was the first to discover the first live cell?
anton von leeuwenkoek, 1676 - called it an animocule.
who discovered the cell wall?
robert hooke, 1665.
large cells?
not active, more likely to be used as storage as its hard for it to be metabolically active. large to store nutrients, eggs, adipose. predators large to consume prey. amoeba, paramecium.
function dictates structure?
plasma membrane is both outlet and inlet for exchange. need monomers, water, oxygen and electrolytes. dispose of metabolic waste.
supply / disposal restrictions?
need enough surface area to service exchange needs. cell size (volume) increases faster than surface area. cells must stay small to supply entire cytoplasm. larger cells don’t do much (egg cells). eggs activated by fertilisation divide into smaller cells.
absorption and exchange?
different shapes can improve surface area / volume ratios. cells specialising in absorbing exchange after shape. microvilli.
processes?
extend branches from the center of the cell.
exons, dendrites?
neuron connections.
pedicels?
filter blood in kidneys.
stereocilia?
detect movement in the inner ear.
cilia?
short, numerous oar like membrane extensions.
pseudopodia?
changing membrane shape to crawl.
flagellum?
resemble cilia, but few and long.
prokaryotes?
unicellular organisms without nuclei, nucleoid present. bacteria, cyanobacteria, archaebacteria. dna coiled but not separated from cytoplasm.
eukaryotes?
dna segregated from cytoplasm by a membrane. unicellular organisms and multicellular fungi, plants and animals.
surface area?
a decreased surface area to volume ratio decreases a cells ability to exchange with the environment.
structure?
phospholipid hydrophobic head and a hydrophobic tail (phospholipid bilayer). two layers hydrophilic top and bottom, hydrophobic center.
barrier?
surfaces allow border with H2O outside, cytoplasm inside. center is barrier to hydrophilic ions and polar molecules.
the permeability of the lipid bilayer?
hydrophobic (nonpolar) molecules such as hydrocarbons can dissolve in the lipid bilayer and pass through rapidly. hydrophilic molecules including ions and polar molecules do not cross the membrane easily. proteins built into the membrane play key roles in regulating transport.
cholesterol?
animal cells, not plants. intermixed with phospholipids. regulates stiffness and flexibility. cholesterol has different effects on cells at different temperatures. at warm temperatures cholesterol limits phospholipids movements. at cool temperatures, cholesterol prevents lipids from becoming packed.
proteins?
float and drift in the bilayer. most functions other than the barrier: transport, signaling, etc.
transport proteins?
transport proteins allow the passage of hydrophilic substances across the membrane.
membrane carbohydrates and cell-cell recognition?
cells recognize each other by binding to molecules. often with extracellular surface carbohydrates. membrane carbohydrates may covalently bond to lipids forming glycolipids or proteins. especially important in signaling and adhesion functions.
cytoplasm functions?
most chemical reactions of the cell, position and move the nucleus and other organelles. vary viscosity for a structural report
cytoskeleton and functions?
types?
microtubules: tubulin for shape and intracellular transport. provide the framework for major transport. microfilaments: actin for membrane shape, contraction. intermediate filaments: proteins vary, support and strength.
microtubules - cilia and flagella?
microtubules control the beating of flagella and cilia.
microfilaments and intermediate - microvilli connections?
crosslinked actin provide support connected by a dense network of intermediate filaments.
nucleus?
eukaryotes only contains chromosomal dna. nucleoplasm: gelatinous matrix inside. nuclear envelope: double membrane with pores. nucleolus: manufactures ribosomes.
endosymbiotic organelles?
eukaryotes only evolved from captured bacteria. at least 2 membranes, own chromosome, and ribosomes. mitochondria: aerobic respiration. (aerobic non-photosynthetic bacterium). chloroplasts: plants and algae only, photosynthesis. (photosynthetic bacterium).
mitochondria: chemical energy conversion.
found in nearly all eukaryotes, site of aerobic respiration. smooth outer membrane and a folded inner membrane.
chloroplast: the capture of energy light?
site of photosynthesis, found in leaves and green organs of plants and cells of algae. key components: thylakoids/granum, outer and inner membrane and inner membrane space, stroma.
core 4?
dna, ribosome, plasma membrane, cytoplasm.
