Midterm 1

Cells and Organelles, Cytoskeleton, Transports, Metabolism

Cytoskeleton

network of microtubules, microfilaments and inter filaments within the cyotplasm

Important Roles of Cytoskeleton

mechanical, structural, transport, motility and signaling function it organizes the cell structure, anchor the organelles and facilitate cellular activities organelles and enzymes can attach to the cytoskeleton and move across the cell it is responsible for the maintenance and modifications of the cell shape

Microtubules

thick hollow rod composed of tubulin proteins the microtubule has an orientation a microtubule can grow shrink in length

Structure of Microtubules

hollow tubes

Protein Subunits of Microtubules

tubulin, a dimer consisting of a-tubulin and b-tubulin

Functions of Microtubules'

maintenance of cell shape cell motility chromosome movements in cell division organelle movements

Fibroblast

type of cell in loose connective tissue that secretes the protein ingredients of the extracellular matrix

Kinesin

moves cargo toward the plus end of the microtubules

Dynein

moves cargo toward the minus end of the microtubules

Centrosome

structure present in cytoplasm of animal cells near the nucleus that functions as a microtubule-organizing center and is important during cell division

centriole

cylindrical structure in the centrosome of an animal cell composed oof 9 microtubule triplets

microfilaments

actin filament thin filament composed of actin proteins acting along or with myosin to cause cell branced

structure of microfilametns

2 interwined strand of actin

protein subunit of microfilaments

actin

functions of microfilaments

maintenance of cell shape changes in cell shape muscle contraction cytoplasmic streaming in plant cells

intermediate filaments

strong and flexible filaments of intermediate size that provide mechanical support of the cell against physical stress

Structure of Intermediate Filaments

fibrous protein coiled into cables

protein subunits of intermediate filaments

one of several different proteins

functions of intermediate filaments

maintenance of cell shape anchorage of nucleus certain other organelles formation of nuclear lamina

plasmodesmata

neighbouring cells of multicellular organisms adhere and communicate to one another

tight junctions

plasma membranes of adjacent cells are bound together by proteins prevents leakage of fluid through the epithelium layers

desmosomes

anchors adjacent cells together through transmembrane proteins that are linked to the intermediate filaments

gap junctions

similar to plasmodesmata in plants cells 6 proteins form a channel and allow the communication of adjacent cells

All living organisma posses….

7 properties: cellular organization, energy and metabolism, reproduction, heredity and evolution, growth and development, regulation and homeostasis, response to stimuli

not considered organisms

virus, pirons, viroids (no cellular organization, internal metabolism, growth or development)

Virus

infectious particle incapable of replication, genome surronede by a protein coat

Prions

infectious agents misfolded version of a normal cellular protein, degenerative disease of the nervous system

Vroids

small infectious circular RNA molecules, replicate using the replication machinery of plant host cell, transmit between cell and individual plants

Carbon

highly abundant on earth, small molecular, bind to 4 atoms

majority of biological

Carbon, Oxygen, Hydrogen, Nitrogen Carbohydrates, Proteins, Fatty Acids, Nucleic Acids

Origin of Life

3500 years ago

Hypotheses

organic molecules necessary for first step in origin of life may have been synthesized from abiotic molecules on early earth

cytophila

first organisms stromatolites are fossils of their photosynthesis

cell theory

basic structural, functional, bioloical unit of organisms smallest unit of life derive from pre-existing cells all organisms made of cells

CRIPR

allows you to change the genome cells

diversity of cellular functions

contain and transmit the genetic material acquistion and conversion of energy feeding and absorption of nutrients structure and support communication and response to environmental stimuli barrier and defense mechanisms transport of molecules

Central Dogma

1956 nucleic acid → nucleic acid nucleic acid → proteins James Watson DNA→ RNA → proteins

multicellularity

eukaryotes evolved around 3200 years

Advantages of Multicellularity

increase surface area from diffusion longer lifespan cell into cell types, tissues, organs protection, feeding, locomotion, reproduction

colonial hypothesis

colonies from through the cooperation of unicellular organisms of the same species, with cells failing to separate/separating and rejoing

3 domains

eukaryotes, archaea, bacteria

eukaryotes

plants fungi animals

eukaryotes: protists

all eukaryotes organisms - neither fungi/plants/animals

archaea

prokaryotes that not bacteria lives in extreme environamtal conditions - extremophiles

ribosomal proteins

are critical for protein synthesis mutations disrupt their amino-acid sequence are selected out

Antoni Van Leeuwenhock

first to describe sizes and movement of cells

Microscopy

Light Microscope Tranmission Electron Microscope Scanning Electron Microscope Fluorescence Microscope

Light Microscope

light does through speciemen image is magnified by refraction through lens

Transmission Electron Microscope

beam of electrons goes through specimen and reveal internal structures thin slices of specimen hardened in resin/frozen

Scanning Electron Microscope

beam of electrons scan surface of specimen coated with gold secondary electrons liberated by sample and detected and converted into electric signal for imaging

Fluorescence Microscope

fluorescent marker: green fluorescent protein (GFP) fluor chemical compound antibody tagged with a fluor molecule specific wavelength

surface/volume ratio of cells

with increase cell size the cell volume increases more rapidly than its surface area diffusion across the membrane depends on its surface area, exchanges between the cell and the environment are more efficient for smaller cells

Similarities: Animal and Plants Cells

genetic info encoded in DNA and using a genetic code plasma membrane made a bilayer of phospholipids transcription and translation of genetic info, including similar ribosomes

Differences: Animal and Plants

Cytoplasm and Cytsol

Prokaryotes: Absence of \_______

nucleus, organelles

Prokaryotes: presence of \_____

nucleoid

EUKARYOTES: presence of \____

nucleus

Extracellular Matrix

animal cells is a network made of glcoproteins, polysaccharids and proteoglycan

collagen fibers

are embedded in a network of proteoglycan

fibronectin

are proteins that attach both the ECM and integrins

Integrins

can transmit information between the ECM and the cyotskeleton

REPRODUCTION AND CELL DIVISION: prokaryotes

asexual through binary fission into two indentical daughter cells

REPRODUCTION AND CELL DIVISION: eukaryotes

sexual reproduction requiring meiosis and fertilization

FLAGELLUM

long cellular appendage specialized for locomotion

FLAGELLUM: Prokaryotes

Flagellum made of flagelin and inserted in the plasma membrane

FLAGELLUM: eukaryotes

projects from the cytoskeleton and covered by the plasma membrane

Organelles: Eukaryotes

any of several membrane - enclosed structures with specialized functions, suspended in the cytosol of cells

Organelles: Prokaryotes

cells lack this compartmentalization they do not have organelles can move within the cell following the cytoskeleton tracks

Nucleus

organelle of eukaryotic cell that contains the genetic material in the form of chromosomes some genes can be found in the mitochondrial chromosomes

Chromatin

complex of DNA and histone proteins making up chromosomes in eukaryotes can condense cell division

Nucleolus

specialized structure in the nucleus, consisting of chromosomal regions containing ribosomal RNA genes along with ribosomal proteins imported from the cytoplasm

Endoplasmic Reticulum

membranous network of sacs that are continuous with the out nucleur membrane

Rough ER

ribosome studded synthesis of proteins that are secreted by the cell or sent to other parts of the cells these secretory proteins are directory during translation into the ER lumen and transported within transport vesicles

Smooth ER

ribosome-free contains many enzymes responsible for many metabolisms symthesis of lipids, phospholipids, steroids, cholesterol, carbohydrate, metabolism

golgi apparatus

tracfficking center manufractures, receives, sorts, modifies, ship many molecules, proteins can mature in the GA polysaccharides can also by synthesized or modified in the GA

lysosome

digestive organelle that contains hydrolytic enzymes content is very acid and lytic enzymes fusion of lysosomes with phagocytosis vesicles allow the digestion of preys or pathogens

Peroxisome

a single- membrane oxidative organelle that contains enzymes that remove hydrogen atoms from substrates and transfer the to oxygen

ROLE of Peroxisome

break fatty acids down into smaller molecules for cellular respiration detoxification by oxidizing alcohol and other harmful compounds glyoxisomes allow seedlings to grow by breaking down the stored fatty acids

Vacuole

large vesicles derived from ER and GA membrane is semi-permeable and allows the transport inside of only very specific molecules

ROLE of Vacuole

storage of nutritious molecules, poisonous molecules, lytic enzymes, pigments, water and ions cell growth, structural support and tendrils through the increase in cell volume

Emdosymbiosis

relationship between to species in which one organism lives inside the cell of another organism

Mitochondrion Plastid

organelle possessing its own membrane circular DNA, their own transcription/translation proteins, ribosomes, proteins similar to those of bateria

Serial Emdosymbiosis

the mitchondrion originates from the phagocytosis of from an aerobic becterium by a archaea cell the chloroplast originates from the phagocytosis of from a photosynthetic becterium by eukaryote

Membranes

plasma membrane constitutes a selective barrier with the environment mitochondria and chloroplasts are organelles with double membrane

Mitochodrion

double membrane - bound organelle that converts chemical energy acquired from the environment into chemcial energy that is directly usable by the cell

Mitochondrion and Eukaryotic

present in almost all cell infoldings of the inner membrane separate the intermemebrane space from the mitochondrion

Mitochondria

posses their own DNA and ribosomes since the origin of the endosymbiosis some gene have been tranferred to the nucleus

Chloroplast

double membrane - bound organellle that converts solar energy acquires from sunlight into chemical energy that can be converted by the mitchondrion into energy that is directly usuable by the cell

intermembrane space

separates both membranes of the chloroplast thylakoids membranous fast and interconnected sacs inside the chloroplast and that are stacked

Lipids

any of a group of large biological molecules, including fats, phospholipids and steroidshydrophobic

Fatty Acids

carboxylic acid with a long carbon chaincan vary in length and in the number and location of double bondscan bond to a glycerol molecule to form a fat molecule

Saturated Fat

solid at room temperature

Unsaturated Fat

lipid at room temperature

Plasma Membrane

memebrane at the boundary of every cell that acts as a selective barrier, regulating the cell chemical compositionbilayers of phospholipids

Roles of Plasma Membrane

compartmentatlizationsite for biochemical activitiesproviding a selectively permeable barriertransporting solutesintercellular interactionenergy transduction

compartmentalization

specialized cellular activites independent from the external environment

site for biochemical activities

many molecules are embedded within the membrane

providing a selectively permeable barrier

controls the molecules that enter or leave the cell

responding to external stimuli

receptors can detect or integrate stimuli → signal transduction

intercellular interaction

adherence, signaling, communication, exchange of molecules