Ch. 4 Cell Structure & Functions Flashcards
what is a cell?
the most basic unit of structure capable of carrying all processes of life
Robert Brown
1st to identify the nucleus in plant cells
Theodor Schwann
1st to state that animals are made up of cells and cell parts
Rudolph Virchow
said that all cells come from preexisting cells
Matthias Schleiden
1st to state all plants are made up of cells and cell parts
Robert Hooke
1st to observe a thin slice of cork & called the compartments “cells”
The Cell Theory (1)
All living organisms are composed of 1 or more cells
The Cell Theory (2)
The cell is the most basic structural unit having the basic properties of life
The Cell Theory (3)
All cells come from preexisting cells
4 main functions of cells
- take in nutrients
- convert nutrients to energy
- get ride of waste
- to reproduce
Prokaryote
cells that have no nucleus, but still have DNA (bacteria)
Eukaryote
cells that have a nucleus containing DNA
Why are cells so small?
as cells grow, the volume increases faster than the surface area if cells were larger: -nutrients cannot enter fast enough -wastes cannot leave fast enough *cell poisons itself*
The 3 main regions of the cell
- cell membrane
- nucleus
- cytoplasm
The Cell Membrane (plasma membrane)
- boundary that gives shape and flexibility
- “selectively permeable”: chooses what to let in/out of the cell
- “fluid mosaic” by allowing lipids & proteins to move around and form pores
- allows interactions and communication with other cells
Types of proteins embedded in the cell membrane
- receptors: ready to accept chemical reactions
- messengers: send messengers
- enzymes: speed up reactions
- carrier/pumps: carry substances back and forth
- (need ATP)
- channel proteins: channel material in and out of cell
- molecular motors: motor proteins help movement
- cell identity markers
- cell adhesion molecules
The Nucleus
protects and contains the heredity molecule DNA
-involved in cellular control and cellular division
The Cytoplasm
semifluid substance between the cell membrane and nucleus
- contains dissolved substances, organelles, and filaments of the cytoskeleton
- “cytoplasmic streaming”: constant motion
what are the external structures of a cell
- glycocalyx
- microvilli
- cilia
- flagella
glycocalyx
cell recognition, adhesion, fertilization, development
microvilli
increases surface area of a cell
cilia
cellular movement and sensations
flagella
locomotion
what are the internal structures (organelles)?
- nucleus
- ribosome
- smooth endoplasmic reticulum
- rough endoplasmic reticulum
- golgi body
- mitochondria
- vesicles
- cytoskeleton
- centrioles
nucleus
cellular control & division
parts of the nucleus
- nucleoplasm
- nucleolus
- nuclear envelope
- chromatin
nucleoplasm
a viscous fluid that fills the nucleus: where chromatin is suspended
- similar to cytosol
nucleolus
a dense irregular shaped region rich in proteins and nucleic acids where ribosomal subunits are made
nuclear envelope
double membrane (two lipid bilayers) that makes the outer boundary of the nucleus - its pores and proteins allow certain substances to enter and leave the nucleus
ribosome
assemble proteins and interpret the genetic code
smooth ER
- produces lipids
- breaks down carbohydrates, fatty acids, and toxins
rough ER
produces, modifies, and transports proteins
golgi body
modifies polypeptides into mature proteins
-sorts, ships, and packaging proteins and lipids in and out of the cell
mitochondria
produces ATP molecules for use during cellular respiration
- have their own DNA and ribosomes, and divide independently of the cell*
- *has two membranes, one highly folded inside the other**
vesicles
transport and stores substances inside the cell
also digests worn out cell parts
cytoskeleton
protein fibers that provide shape, support and movement for the cell
centrioles
move cellular parts during cell division; where microtubules are grown
How do cells communicate?
through cellular junctions
adhering junctions
holds cells together to each other
gap junctions
provide communication between cells
hormones and/or neurotransmitter
tight junctions
prevent leakage between cells
the cytomembrane system
a series of organelle (ER, golgi body, and vesicles) in which lipids are made and polypeptide chains are modified into proteins to be used in the cell/out of the cell
plant cell differences
- cell wall
- vacuole
- plastids
cell wall
gives support and protection to the plant cells
central vacuole
stores H2O, enzymes, and waste
**when plant is water, vacuole will fill up with water and push the organelles against the cell membrane
plastids
stores food and absorbs different wavelengths of light
chloroplast
the main plastid in plant cells
-makes sugars (in plants and some protists)
chromatin
if DNA is balled up in a non-dividing cell
chromsome
if DNA is ready or going in to either meiosis or mitosis in a dividing cell
chromatin turns into chromosome
The Cytoskeleton
complex system of interconnected protein filaments
- parts of the cytoskeleton reinforce , organize, and move cell structures
parts of the cytoskeleton
- microtubule
- microfilament
- intermediate filament
microtubule
long, hollow cylinders that’s function is movement
- can rapidly assemble and disassemble
- *consist of subunits of the protein tubulin**
microfilament
fine fibers that reinforces cell membrane & connect and support the plasma membrane
- functions in cellular movement,contraction, shape changes and migration
- *consists primarily of the protein actin**
- part of the cell cortex*
cell cortex
region of cytoplasm just inside the plasma membrane
intermediate filaments
stable cytoskeletal element in animal cells (and some protists)
- lends structure and resilience to cells and tissues
- different types are assembled from different fibrous proteins*
extracellular matrix
a large network of proteins and other molecules that shape, support, and give structure to cells and tissues in the body
ex. plant wall
primary wall
thin walls containing cellulose produced by growing cells (thin walls provide flexibility as the organism grows)
- all plants have a primary cell wall
middle lamella
the layer that cements the primary wall to adjoining plant cells together
- all plant cells have a middle lamella
- made up mainly of pectin ( a complex set of polysaccharides)
secondary wall
the sturdier wall that develops in many plant cells; but not all
- only develops after primary wall is complete and organism has stopped growing
- has permanent rigidness that gives the plant support
- made up cellulose, lignin and other polysaccharides *
lignin
compounds most present in secondary plant walls
- gives land plants its wood texture and color
- gives plants its strength and rigidness
- protects plants from pests and pathogens
plasmodesmata
a channel passing through the plant wall
- allows adjacent plant cells to communicate
- similar to gap junctions in animal cells*
