cell structure

what is cell theory

1. All organisms are composed of one or more cells

2. Cells are the smallest living things and the basic unit of organization of life

3. Cells can only come from pre-existing cells.

why is cell size limited

small size allows cells’ metabolic processes occur rapidly to maintain homeostasis

what happens as the cell size increases

the relative surface area decreases and demand for nutrients increases

what determines the speed at which nutrients and wastes are moved into or out of the cell

surface area available, temperature, the concentration gradient, and distance that the nutrients have to travel

what is the SA:V

surface area to volume ratio

.

.

what happens when cell becomes to large

they have to divide or die

how do some cells increase their surface area

they have in-foldings (especially cells involved in absorbtion)

how do you find the SA:V

calculate the surface area and the volume of a cell, divide the surface area by the volume and set it up as a proportion

what does a high SA:V ratio mean

the cell is more efficient

what does a low SA:V ratio mean

the cell is less efficient

what is a prokaryote

simple, single celled organism

what is a eukaryote

complex, single or multi-celled organisms

did prokaryotes or eukaryotes come first

prokaryotes

when did prokaryotes first emerge

about 3.8 billion years ago

what are the features of prokaryotes

they have a cell membrane, cytoplasm (cytosol), ribosomes, cell wall and naked DNA

they have no membrane-bound organelles

what are examples of prokaryotes

E. coli, H. pylori

what does the cell wall do

it prevents dehydration, protects, and provides structure 

what are the features of eukaryotes

they have membrane-bound organelles like a nucleus, chloroplast, mitochondrion, and endoplasmic reticulum. they also have a cell membrane, cell wall, cytosol, and ribosomes like prokaryotes

what are examples of eukaryotes

plant and animal cells

what are organelles

sub-cellular structure that have specific jobs to perform in the cell,

what organelles have a double membrane

nucleus, chloroplasts, and mitochondria

what organelle doesn’t have a membrane

ribosomes

what makes up the organelle membranes

phospholipids

what is the plasma/cell membrane

a phospholipid bi-layer that controls the movement of nutrients and wastes in and out of the cell

why does the cell membrane have to be large

they have to be large enough (surface area) to efficiently transfer materials

what do some cell membranes do to increase their surface area

they have folds in the membrane increase the efficiency and absorption

what is the cytoplasm/cytosol

the thick, semi-solid fluid that is found inside the cell (70-80% water)

what is inside the cytoplasm

the organelles and all the nutrients the cell needs (glucose, amino acids, lipids)

what occurs in the cytoplasm

protein synthesis

what is the nucleus

the organelle that houses the DNA of a cell and is seen as a roundish organelle

what is the nuclear envelope

the phospholipid bi-layer membrane that surrounds the nucleus

what does the nuclear envelope have

contains permanent pores to allow RNA to travel in and out of the nucleus

what is the nucleoplasm

the thick, semi-solid liquid found within the nucleus

what does the nucleolus do and where is it found

makes ribosomal RNA (rRNA) and proteins

it’s found in the center of the nucleus and looks like a darker ball

what is chromatin

unwound DNA in the nucleus

what is a chromosome

wound DNA in the nucleus

what is found in the nucleus

nucleolus, chromatin, chromosomes, nucleoplasm, and is surrounded by the nuclear envelope

what does a ribosome do

protein synthesis

are ribosomes membrane-bound organelles

no!

where are ribosomes found

they are free floating in the cytoplasm or attached to endoplasmic reticulum

what kind of ribosomes do prokaryotes have

70S (smaller)

what kind of ribosomes do eukaryotes have

80S (larger)

what makes up ribosomes

2 subunits of large and small and ribosomal RNA (rRNA)

what types of cells have the most ribosomes

cells that make proteins (like skin cells)

what is mitochondria

organelle that make ATP which is used for energy within the cell

what is ATP

adenosine triphosphate

what type of cells are ATP found in

they’re found in cells that undergo aerobic respiration (use oxygen)

what is the phospholipid bilayer like in mitochondria

it has a phospholipid bi-layer with embedded proteins for the electron transport chain and inner folds (cristae)

the outer layer is smooth

what is the cytoskeleton

what is the matrix

fluid in the mitochondrion (where the Kreb’s cycle occurs)

what are vacuoles

large sacs that function in storage and transport

what do vacuoles do in plants

they store water

what do contractile vacuoles do

they regulate water concentrations and will pump out excess water by contracting

what eukaryotic cells are centrosomes found in

animal cells

what are centrosomes

organelles that function in cell division (thought to pull the duplicated chromosomes to the poles during cell division)

what is inside centrosomes

centrioles

what do centrioles do

pull chromosomes to opposite poles during meiosis/mitosis

what type of eukaryotic cells are lysosomes found in

animal cells (l)

what are lysosomes

organelles that have hydrolytic enzymes used in the breakdown (lysis) of things

how do lysosomes protect the cell

they aid in destroying foreign proteins (antigens) and boost immunity

what is the pH in lysosomes like

it’s lower for the digestion of macromolecules

what eukaryotic cells are cell walls found in

fungi and plants cells

what is the cell wall

rigid structure made of cellulose (plants), chitin (fungi), or peptidoglycan (prokaryotes) that surrounds the cell

what does the cell wall do

it protect the cell, prevent dehydration of the cell, and also to provide support to the cell

what eukaryotic cells are chloroplasts in

plant cells

what do chloroplasts do

photosynthesis and ATP synthesis

what are thylakoids

discs filled with a fluid called stroma used in light-independent reactions

what are grana

stacks of thylakoids

what is chlorophyll

pigment that captures and converts light energy into sugar and oxygen

what structures are in chloroplasts

thylakoids, stroma, grana, and chlorophyll

what are the two types of endoplasmic reticulums

smooth and rough

what are the features of the smooth er

makes carbs, lipids, steroids, helps with detoxing meds, and has no ribosomes attached

what are the features of the rough er

has ribosomes attached and help “finish” or modify proteins

what does the golgi apparatus do

it sorts, packages, and tags lipids and proteins before they are transported

what types of cells have lots of golgi

cells that secrete saliva

what is the endomembrane system

organelles that are continuous with the plasma membrane and work to modify, package, and transport lipids and proteins

what organelles are part of the endomembrane system

endoplasmic reticulum, Golgi apparatus, lysosomes, nuclear envelope, and vesicles

what is the cytoskeleton

protein filaments that provide structure and support to the cell

what is cilia

hair like organelles that do locomotion

what does the cytoskeleton do

they aid in transporting vesicles in the cell and make and move flagella and cilia

what is flagella

tail like organelle that does locomotion

what is a vesicle

structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer

-

-

what is Theory of Endosymbiosis

an evolutionary theory that the mitochondria and chloroplast were once prokaryotic cells that were engulfed by a eukaryotic cell

what evidence supports the theory of endosymbiosis

mitochondria and chloroplasts have different dna from the dna in the nucleus and have a double membrane (indicates that in addition to their own membrane, these organelles picked up some of the plasma membrane when engulfed)

what is apoptosis

cell death/suicide

when does apoptosis occur

when cells have been injured, have undergone mutations, are no longer functional

what is the extracellular matrix

the space outside of cells

what does the extracellular matrix do

holds cells together and allow cell-to-cell communication and contains wastes released from the cell

what are the types of cell junctions

plasmodesmata, tight junctions, desmosomes, and gap junctions

what are the characteristics of plasmodesmata junctions

they’re found in plants and are composed of channels between neighboring cells for the movement of water and nutrients

what are the characteristics of tight junctions

they’re found in animal cells and are watertight channels between adjacent cells

what are the characteristics of desmosomes junctions

they’re found in animal cells; protein filaments from one cell enter into the plasma membrane of the adjacent cell

what are gap junctions

found in animal cells and transport nutrients