chapter 2: cells

cells

the basic unit of all organisms

two basic type of cells

prokaryotes and eukaryotes

what are the four common traits of eukaroytes and prokaryotes cells

1. surrounded by a plasma membrane
2. contain a semifluid substance called cytoplasm
3. contain structure called chromosomes DNA
4. contain ribosomes

what is the difference between a eukaryote cell and a prokaryote cell in terms of **size**

eukaryotic cells are larger than prokaryotic cells

what is the difference between a eukaryote cell and a prokaryote cell in terms of **organelles**

eukaryotic cells contain **organelles** inside of them; prokaryote cells do not

\
**this includes the nucleus**

what is the difference between a eukaryote cell and a prokaryote cell in terms of how **quantity of** **cells** contained in the organism

eukaryotes are multi-cellular organisms while prokaryotes are single cellular organisms

what is the difference between a eukaryote cell and a prokaryote cell in terms of **chromosomes**

Eukaryote chromosomes are contained **within the nucleus** prokaryote chromosomes do not

what is the difference between a eukaryote cell and a prokaryote cell in terms of **the number of chromosomes**

eukaryote chromosomes vary in number from organism to organism while prokaryotes have a single circular chromosome

surface area

determines the amount of substances the cell can take in and the amount of waste it can release

volume

determines the amount of chemical activity it can carry out

what is the ratio of surface area to volume and why?

surface area is **larger** than volume

\
allows more materials to move in/out of the cell so chemical reactions can occur

organelles

specialized internal cell structures that carry out specific cell functions

what type of cell processes do organelles carry out?

essential cell processes like protein synthesis, energy transformation, digestion of food, excretion of wastes, and cell division

protists

first eukaryotic cells

single-celled eukaryotes

they can range from protozoans to algae

what eukaryotes are multicellular

fungi, plants, animals

what does the nucleus contain

contains the DNA

what does DNA do

stores information used to make proteins for cell growth, function and reproduction

\
the manager

ribosomes

organelles that help manufacture proteins

what are ribosomes made of

RNA and protein

\
(not bound by a membrane)

where is the site of ribosome production

nucleolus

what leaves the nucleus through the nuclear pores?

ribosomes

what structure is DNA packed into

chromosomes

how do cells become specialized

turning on, or expressing certain genes in DNA

endomembrane system

made up of organelles that make protein, process them, and ship them to where they are needed, inside or outside of the cell

what organelles are included in the endomembrane system

nucleus

rough/smooth ER

golgi apparatus

lysosomes

endoplasmic reticulum (ER)

a membrane of folded sacs and interconnected channels that serves as the site of protein and lipid synthesis

rough ER

ribosomes are attached to it’s membrane

\
the attached ribosomes will synthesize proteins

smooth ER

does not have ribosomes on its surface

\
makes lipids, detoxifies the cells, and stores calcium ions

how does the golgi apparatus and the ER work together?

the golgi receives the transported vesicles that bud off from the ER and contains proteins

golgi apparatus

takes the substance from the ER (proteins) and modifies them chemically in order to mark them and sort them into different batches depending on their destination

\
the finished product will either move to the lysosomes, inserted into the plasma membrane, or dumped out of the cell

lysosomes

contain hydrolytic enzymes used to breakdown other substances

\
used to digest excess or worn-out organelles, food particles, and engulf viruses or bacteria

peroxisomes

special type of lysosomes

\
contains an enzyme which produces hydrogen peroxide and breaks it down

plasma membrane

phospholipid bilayer with proteins and other molecules interspersed throughout

three main functions of the plasma membrane

selective permeability

protection

structural support

phospholipid

amphiphilic having both hydrophobic and hydrophilic regions

contains a hydrophilic head and a hydrophobic tail (fatty acid)

why do phospholipids form a bilayer when placed in water?

to protect the hydrophobic tails from the water and then the hydrophillic heads can interact with the water on the inside and outside of the cell

passive transport

movement of substances from an area of high concentration to an area of low concentration without the requirement an energy input

active transport

the movement of substances from an area of low concentration to an area of high concentration and requires an input of energy

exocytosis

used to excrete a large molecule from the cell

the vesicle that encloses the proteins fuse with the plasma membrane and the vesicle then opens up and spills their contents outside of the cell

endocytosis

the cell takes in macromolecules or other particles by forming vesicle or vacuoles from its plasma membrane

chloroplasts

reside in plant cells and some protists and convert solar radiation into energy stored through **photosynthesis**

mitochondria

resides in all eukaryotic cells and converts chemical energy from glucose into ATP through **cellular respiration**

what makes mitochondria and chloroplast different from other eukaryotic organelles

they have their own DNA, their own ribosomes, and have a double cell membrane

Endosymbiotic Theory

the mitochondria and chloroplast were once prokaryotes that got engulfed by another prokaryote

\
they were both considered *bacterias*

\
when they got eaten by another prokaryote they got dragged by one prokaryote’s cell membrane around theirs making the **double membrane** and allowed the new eukaryote to make their own ATP/be able to do photosynthesis to make its own food

\
evolution of eukaryotes

what is the evidence of endosymbiotic theory

the mitochondria and chloroplasts can arise only from preexisting mitochondria and chloroplasts and cannot be formed in a cell that lacks them

\
they both have their own DNA and resembles the DNA of bacteria or prokaryotes (single circular DNA)

\
mitochondria and chloroplasts have their own ribosomes which closely resembles bacteria ribosomes than eukaryote’s ribosomes

Mitochondrial Eve

DNA is passed through from mother to child and you **inherit** your mitochondria from your mother only

\
the egg contains our mothers organelles and only dad’s sperm contains the chromosomes

\
mitochondrial DNA is a way to trace maternal heritage through a family or through a species and we can **trace all humans back to her** (eve) through mitochondrial DNA

chloroplasts

organelles convert solar energy to chemical energy through photosynthesis

three major compartments of chloroplasts

thylakoids

stroma

intermembrane space

two major compartments of the mitocondria

matrix

intermembrane space

vacuoles

membranous sacs which come in different shapes/sizes and have a variety of functions

central vacules

in plants store water which gives their strength and rigidity

stores vital chemicals, pigments, and waste products

full central vaculoes

take over the cytoplasm and push the organelles to the side

what happens when plants do not get enough water

the vacuoles are not full and the cytoplasm is pulled away from the wall, the plant wilts, limps, and droops

contractile vacuoles

found in certain single-celled protists

\
acts as **pumps to expel excess water** from the cell and keeps the cell from exploding

cytoskeleton

a network of fibers within the cytoplasm

\
provides structural support and are involved in various types of cell movement and motility

cell wall

an outer layer besides the plasma membrane

what are cell walls made out of

cellulose

fungal: chitin

cell junctions

allows cells to communicate and pass substances to one another

how do plant cell junctions connect

plasmodesmata

plasmodesmata (plural)

tight junctions

bind cells together into leakproof sheets

adhering junctions (desmosomes)

fasten cells together into strong sheets and are somewhat leakproof

gap junctions

allow substances to flow from cell to cell

what do plant cells have that animal cells do not have

cell wall, chloroplasts, vacuoles