Bio Exam 2

Robert hooke

coined cells in 1600s

cell

smallest self-sustaining unit of life, exhibits all tenets of life

Zacharias Janssen and Sons

first compound microscope Holland, 1595, most microscopes we look at

Anthony Van Leeuwenhoek

built single lens microscope (magnifications -200x), first to observe blood cells, bacteria, sperm cells, protozoa

evidence refuted spontaneous generation

cell theory

1. cells are the smallest unit of life

2. all life is composed of cells

3. all cells arise from other cells

does not address complexity of cells

cell theory scientists

Dr. Matthias Schleiden, Dr. Theodore Schwann, Rudolph Virchow

Dr. Matthias Schleiden

botanist, 1838, suggested plants are composed of cells

Dr. Theodore Schwann

zoologist, 1839, suggested all animals come from cells

Rudolph Virchow

physician, 1855, all cells come from other cells

prokaryotic

bacteria, archaea, 3.5 billion years ago, no nucleus or organelles, smaller

eukaryotic

protists, fungi, plants, animals, 2.1 billion years ago, nucleus and organelles, larger

plasma membrane

all cells are bounded by a membrane of phospholipids

cytosol

polar, thick, jelly-like fluid that cell components are suspended in

cytoskeleton

protein based filaments in cytoplasm that maintain structure of cell

genome

all cells have one or more chromosomes carrying genes made of DNA

ribosomes

tiny structures that build proteins according to the instructions from the genes

prokaryotic layer structure

prokaryotic layer structure

capsule

sticky coating for protection

fibriae

attachment structures

flagella

help cell move

cell wall

protects and keeps shape

plasma membrane

surrounds cytoplasm and cell machinery

nucleoid

contains single circular bacterial chromosome

ribosomes

synthesize proteins

Eukaryotic plant cell

specialty- chloroplasts, cell walls (composed of cellulose), vacuoles

Eukaryotic animal cell

specialty- lysosomes (bubbles of digestive enzymes surrounded by membranes)

organelles

membrane-bound structures that perform a specific function, double membrane bound nucleus

plasma membranes

physically separate the cell interior from the extracellular environment, define organelles in eukaryotes, very thin and see through

amphipathic macromolecule

hydrophobic and hydrophilic regions (phospholipids)

phospholipid bilayer

two layer sheet of phospholipids that make up cell membranes, Hydrogen bonds hold heads of phospholipids together

fluid mosaic

flexible, self-sealing, and can fuse with other membranes, not static rigid sheets

plasma membrane is a fluid mosaic

fluid because molecules can move freely past one another

mosaic because of diversity of proteins in membrane

surface proteins

pumps, receptors, help regulate traffic across membrane, perform other functions

plasma membranes

define compartments and organelles of eukaryotes, regulates passage of materials, participates in biochemical reactions, receives info about environment, communicate with other cells, act as part of energy transfer and storage

cytosol

cellular filling liquid, life sustaining chemical reactions, storage, suspends organelles in eukaryotes

Central Dogma of Biology

true of all cells

• chromosomes are pieces of DNA with set sequence of genes

• genes are copied from DNA to mRNA

• ribosome moves along mRNA, translating genetic message into a protein with a specific Animo acid sequence

relationship with DNA

• DNA is wound around histones, translating genetic message into a protein with a specific amino acid sequence

• an entire linear strand of DNA coiled into chromatin is a chromosome

cytoskeleton

network of protein fibers extending throughout cytoplasm

• helps a cell maintain shape, both skeleton and muscles for cell, endocytosis, lysosome transport

cytoskeleton is static, not dynamic

can be quickly dismantled and reformed in new location

• removing protein subunits/reattaching them

• rearrangement can provide rigidity, change shape of cell, cause whole cell or parts to move

microtubules

composed of pairs of different polypeptides in a helical arrangement

intermediate filaments

composed of ropelike bundles of various proteins

microfilaments

composed of actin proteins that resemble twisted double strands of beads

functions of cytoskeleton

involved with transport of materials in cell, pushing/pulling chromosomes during mitosis, protist crawling movement

ribosomes

small complexes of protein and RNA that translate genetic info into amino acid sequence of a protein, part of central dogma, free floating in cytoplasm

ribosome subunit

sandwich mRNA, pulls mRNA through it and matches to corresponding amino acid

endomembrane system

nucleus, ER, Golgi apparatus, lysosomes

nucleus

home of genomic DNA and nucleus

nucleolus

inside nucleus, makes pieces of ribosomes

nuclear envelope (double membrane), pores in envelope regulate entry and exit of materials

ER

produces proteins (lipids primarily), physically connected to nuclear envelope

rough ER

protein synthesis, studded with ribosomes

1. a ribosome links amino acid

2. proteins are modified in ER

3. secretory proteins depart

4. vesicles bud off from ER

smooth ER

lacks ribosomes, produces phospholipids and steroids, important in liver to detoxify and drug metabolism

golgi apparatus

receives vesicles of proteins and lipids from ER, stores, packages and distributes them to their final cellular destination

golgi apparatus movement

1. transport vesicles from ER, products (polypeptides), reach the golgi and fuse with golgi membrane

2. polypeptides dumped from vesicle into folded cavity of golgi body

3. modified by other enzymes in golgi, repackaged in vesicles and shipped to cytoplasm

mitochondria

powerhouse of cell, key role in making ATP, extract energy from food and store it in bonds of ATP

mitochondria structure

double membrane- outer and inner layer

cristae

folded inner membrane studded with respiratory complexes (essential energy hubs)

intermembrane compartment

between cristae and outer membrane

matrix

gel that fills space within cristae, citric acid cycle

chloroplasts

plants only, converts solar energy into chemical energy, makes glucose needed for mitochondrial function, makes own ATP

chloroplast structure

double membrane

stroma

fluid inside (important enzymes suspended)

thylakoid

stacks of continuous membranes studded with photosystems

chlorophyll starts photosynthesis here

endosymbiont theory

chloroplasts and mitochondria were once individual distinct prokaryotes and over time became interdependent evolving into a single organism with inseparable parts

endosymbiosis

Dr. Lynn Margulis, mitochondria and chloroplasts were once individual prokaryotic cells

endocytosis

cells engulfing a thing by wrapping around it (cytoskeleton is responsible)

symbiogenesis

“becoming by living together” coexisting species evolve into new organism

evidence

mitochondria and chloroplasts are similar to bacteria

their replication occurs through binary fission, have their own DNA and ribosomes, circular plasmid DNA, sensitive to same antibiotics that kill prokaryotic pathogens