Unit 2- An Introduction to the Cell

Cell

the smallest most basic unit of living organisms, the simplest structure that exists as an independent unit of life

Unicellular

single cell

Multicellular

more than one cell

Cell theory

similarity in the microscopic organization of all living organisms, all organisms are made up of cells, the cell is the fundamental unit of life, cells come from preexisting cells, unites all forms of life

the fundamental unit of life

the simplest entity we can define as living-reproduce, respond to environment, harness energy, evolve

Cell membrane

the boundary between the interior of the cell and the nonliving exterior, define compartments within eukaryotic cells

Homeostasis

the active maintenance of stable internal conditions, maintained by the cell membrane, important for cells and organisms, temperature, heart rate, blood pressure, blood pH, and water content, active energy-using process

Proteins

make the cell's internal architecture, shape, ability to move, and chemical reactions

Ribosomes

complex structure, the site where a protein is assembled, translates RNA, made up of RNA and protein, a small unit and a large unit, 3 types of ribosomal RNAs and 20-50 types of ribosomal proteins

Central dogma

the path from DNA to RNA to protein, the basic flow of info on all cells, a key concept of biology

Metabolism

the entire set of chemical reactions by which cells transfer energy from one form to another and build and breakdown molecules

Adenosine triphosphate (ATP)

a chemical form that stores energy, enables cells to carry out functions, used for growing, division, and transfer of substances in and out of cells

Catabolism

a set of chemical reactions that break molecules into smaller pieces

Anabolism

a set of chemical reactions that build molecules from smaller units, require energy

Nucleus

membrane-bound space that contains the genetic material of the cell

Nuclear membrane

controls substance moving in and out of the nucleus

Cytoplasm

the space outside of the nucleus

Eukaryotic

cells within a nucleus

Domain

groups of organisms. bacteria, eukarya, and archaea

Prokaryotic domains

small size, reproduce rapidly, obtain energy and nutrients-bacteria and archaea, can only use passive or active transport

Plasma membrane

surrounds the cell wall- helps keep its shape

Bacteria cell wall

thick peptidoglycan or thin lipid layer

Flagella

structures of their surface to help them move

Plasmids

small circular molecules of DNA, few genes, transformed through pili, extend from one cell to another when exchanging plasmids, hold info about environmental advantages because it can spread quickly

Eukarya

animals, plants, fungi, protists (single-celled microorganisms)

Nuclear membrane

allows for more complex regulation of gene expression

Organelles

membrane-defined compartments, that divide cell contents

Cytosol

jelly-like material outside of the nucleus and organelles

Cilia

a rod like structure that extends from the cells

Nonmotile cilia

cilia that don’t move, sensor function

Motile cilia

cilia that move

Surface area

the total amount of area of the outer surface of an area

Internal membranes

define the subcellular compartments/ organelles, each with a specific function and organization

Membrane bridges

connectes membranes within a cell

Vesicles

small membrane-enclosed sacs that transport substances within a cell or from the interior to the exterior of the cell, form a budding from an organelle, join an organelle and fuse with its membrane

Endomembrane system

made up of interconnected membranes of the cell or connected by vesicles, can change shape quickly, divides the cell interior into 2 parts, including the cell membrane, nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, and vesicles

Plant endomembrane

continuous between cells through intercellular connections

Cytoskeleton

protects and gives structure to the cell, can be remodeled quickly which allows cell shape to change quickly

Nucleus

the innermost organelle of the endomembrane, protects the DNA

Nuclear envelope

defines the boundary of the nucleus, 2 lipid bilayer membranes

Nuclear pores

perforate the inner and outer nuclear envelope membranes, large protein complexes with an inner passageway that regulates which molecules move into and out of the nucleus, essential for communication between the nucleus and the rest of the cell

Endoplasmic reticulum (ER)

an organelle made up of interconnected tubules and flattened sacs, extremely convoluted membrane, involved in the production of proteins and lipids, bound with 1 membrane which is continuous with the nuclear membrane, produces many of the proteins and lipids used inside and outside the cell

Lumen

the interior of the organelle or cell

Rough endoplasmic reticulum

studied with ribosomes, the site of RNA protein synthesis

Enzymes

proteins that speed up rates of chemical reactions

Smooth endoplasmic reticulum

the site of fatty acid and phospholipid synthesis, predominates in cells specialized for the production of lipids- many synthesize steroid hormones

Golgi apparatus

made up of cisternae sacs, modifies and sorts proteins and lipids produced by the ER, usually where vesicles go after the ER, part of the pathway of modification of proteins and lipids, modifies proteins and lipids, sorting, adds carbohydrates to proteins and lipids

Lysosomes

specialized vesicles derived from the Golgi apparatus, degrade damaged and unneeded macromolecules, have a key role in intracellular digestion and recycling of organic compounds, involved in programmed cell death

Nucleolus

makes mRNA and also holds ERNA and rRNA

Chromatin

DNA or cell information that is ready for use

Chromosomes

DNA or information ready for transport around the cell

Glycoproteins and glycolipids

sacs that make up the majority of the Golgi apparatus

Antigens/ recognition factors

carbohydrates added to proteins and lipids, like a badge

Endosymbiotic theory

bacteria was eaten and instead of being broken down lived inside of the organism, why animal cells don't have a cell wall, also why mitochondria and chloroplasts are fully separate from the endomembrane system

Mitochondria

the site of cellular respiration, harness energy stored in the carbohydrate and other organic molecules and transfer it to the form ATP, not part of the endomembrane system

Cellular respiration

a series of chemical reactions in which organic molecules are broken down and the energy is stored as ATP, takes place in the mitochondria, oxygen is consumed and carbon dioxide released

Anatomy of a mitochondria

rod-shaped with 2 membranes, outer and highly convoluted inner membrane which increases function

Intermembrane space

space between the inner and outer membranes

Mitochondria matrix

space enclosed by the inner membrane

Chloroplasts

organelles that capture sunlight energy to synthesize simple sugars, present in plant cells and green algae, have an inner and outer membrane

Photosynthesis

the capture of sunlight to synthesize simple sugars, carbon dioxide is consumed and oxygen is released

Thylakoid

inside of chloroplasts, look like flattened sacs, grouped into structures called grana, very convoluted for increased function

Grana

in the thylakoid, connected to one another by membrane bridges so they enclose a single interconnected compartment

Thylakoid membrane

where the light from the sun is turned into chemical energy

Chlorophyll

light-collecting pigment molecule in the thylakoid membrane, green in color

Cytoskeleton

a system of protein filaments, that provides internal support for cells and tracks within the cell for transport of vesicles and other organelles, determines the cell’s shape, allows some cells to change shape, move about, and transport substances within the cell

Microtubules and microfilaments

cytoskeletal elements, long chains of polymers made up of protein subunits, allow cells to change shape, move about, and transport substances

Microfilaments

present in various locations of cytoplasm, extensively branched just beneath the cell membrane, play an important role in maintaining cell shape,
log bundles form a band that extends around the circumference of epithelial cells

Microtubules

hollow tube-like structures, that help maintain cell shape and internal structure, in animal cells, they radiate outward from a microtubule organizing center to the cell periphery, helps cells withstand compression, many organelles tether to these to be guided to organelle arrangements

Cell wall

present in plants, algae, fungi, and bacteria, made up of carbohydrates and proteins but mostly polysaccharide cellulose, maintains the cell shape and size, protection, and structure, outside the cell membrane, rigid and resists expansion

Turgor pressure

the force exerted by water pressing against an object, a result of water moving into cells surrounded by a cell wall, provides structural support and protection for cells

Plant vacuole

in plants and fungi cells, absorbs water and contributes to turgor pressure, why plants wilt, can store nutrients, ions, and water, why plant cells are usually larger

Fungi cell wall

chitin

Bacteria cell wall

peptidoglycan

Volume

the total amount of space an object occupies

Microplasma

a bacteria, the smallest free-living organism

Surface area

describes a flat 2D surface

Allometry

increase in size and change in shape, what happens in the bio world

Isometry

increase in size but shape overall kept

Diffusion

the movement of molecules from areas of high to low concentration, fast over short distances yet incredibly slow and ineffective over long distances

Bulk flow

the movement of a fluid driven by pressure differences, moves oxygen, nutrients, and hormones, allow plants and animals to be have different sizes, shapes, and functions

Lipid bilayer

formed in an aqueous or watery environment, made up of lipids (phospholipids), proteins, cholesterol, and carbohydrates, formed by a less bulky head and 2 lipid-tailed phospholipids, chains come together with heads on the outside, form all cell membranes, self-healing

Phospholipids

a glycerol backbone attached to a phosphate group and 2 fatty acids, the head is hydrophilic and the tail is hydrophobic, nonpolar, and doesn’t form hydrogen bonds with water, are amphipathic, make up the membrane bilayer, when put in water they form a bilayer in a liposome shape

Amphipathic

having hydrophilic and hydrophobic regions

Membranes as dynamic

membranes can perform lateral movements of lipids and other membrane components, help vesicles break off and be absorbed, allows shape change, movement, and engulfment of particles, Van der Waals forces allow phospholipid tails to associate and move

Long phospholipid tail

makes the membrane less fluid

Number or carbon-carbon bonds

makes phospholipid chains unsaturated and therefore less stable and more fluid

Cholesterol

amphipathic and participates in the membrane bilayer, at higher temperatures, the cholesterol membranes become more stable and less fluid, helps temperature not drastically change membrane fluidity (homeostasis)

Lipid rafts

lipids formed into defined patches, bilayers aren’t uniform and rather made up of different rafts

Lipid flip-flop

spontaneous transfer of lipid between bilayer layers, very rare, the hydrophilic head would have to pass through the hydrophobic area, why different layers have different components

Transport proteins

move ions and molecules that can't cross on their own across the membrane

Energy harnessing

electrons pass along the membrane to eventually be used as energy for the cell

Receptor proteins-

allowed the cell to receive signals from the environment, some act as enzymes and others help maintain structure and shape

Integral membrane proteins

permanently associated with the cell membrane and can’t be removed without destroying the membrane

Peripheral membrane proteins

temporarily associated with the membrane or integral membrane proteins through weak noncovalent bonds, easily separated, help proteins cluster in lipid rafts, transmit signal from the environment

Transmembrane proteins

the main type of integral membrane proteins, span the entire bilayer and have 2 hydrophilic regions on either end and a hydrophobic piece in the middle, the hydrophobic piece holds the proteins in place, acts for the outer hydrophilic end to receive signals, and sends them through the hydrophobic piece

Glycoproteins

a carbohydrate covalently linked to a protein, move freely around the cell

Glycolipids

a carbohydrate covalently attached to a lipid, move freely around the cell

Fluid mosaic model

inspired by lipids, proteins, and carbohydrates freely moving in the membrane, the lipid bilayer is a structure within which molecules have laterally (fluid) and is a mixture (mosaic of various components)

Liposome

formed when phospholipids are placed in water with a natural pH, form a spherical shape that resembles a cell