The cell Flashcards
The cell def
Smallest basic unit of life capable of maintaining homeostasis- “biological self balance”, keeps a stable internal environment when external changes occur.
types of organisms with Prokaryotic cell
unicellular
types of organisms with Eukaryotic cell
unicellular + multicellular
are Prokaryotic cells dependent on surrounding cells
independent
are Eukaryotic cells dependent on surrounding cells
dependent
Prokaryotic cells size
1-3 mm(micrometers)
Eukaryotic cells size
10-30 mm(micrometers)
does a Prokaryotic cell have a nucleus?
no
does a Eukaryotic cell have a nucleus?
yes
DNA storage in a Prokaryotic cell
in the cytoplasm
DNA storage in a Eukaryotic cell
in the nucleus
DNA structure in a Eukaryotic cell
in chromosomes
DNA structure in a Prokaryotic cell
circular
does a Eukaryotic cell have organelles?
yes, has membrane-bound organelles
does a Prokaryotic cell have organelles?
no, doesn’t have membrane-bound organelles
does a Prokaryotic cell have a cell wall?
most do
does a Eukaryotic cell have a cell wall?
in plant and fungi cells, not in animal cells
cell division in a Eukaryotic cell
mitosis/ meiosis
cell division in a Prokaryotic cell
fusion/ budding
cytoplasm composition
cytosol + organelles
nucleus structure
is A double-membrane organelle (two phospholipid bilayer).
The membrane is highly selective and separates it from the cytoplasm.
The nucleus membrane contains nuclear pores, which allow passage in and out of the nucleus.
nucleolus def
a darker area in the nucleus, a highly active area where synthesis of RNA takes place.
nucleus Functions:
Contains the genetic code DNA/chromosomes
DNA replication
RNA transcription
Ribosomes def
A protein factory composed of two sub-units - small and large. the number of ribosomes in a Cell depends on its metabolic demand.
the 2 types of ribosomes:
Free floating ribosomes - moving freely in the cytoplasm, create proteins for the cell.
RER bound ribosomes - located on the RER, create exported proteins and cell membrane proteins.
ribosome main Function
Protein synthesis.
small and large subunit of ribosome sizes in bacteria;
30s
50s
small and large subunit of ribosome sizes in humans;
40s
60s
RER def
A membranous continuation of the nuclear membrane, that is overlapping itself. Under the microscope the RER appears rough due to the high content of ribosomes attached to the membrane.
The internal space between the membranes of the RER is called the…
ER lumen.
RER Function
Part of protein synthesis- here, proteins undergo modification by adding sugars to the proteins in the lumen and get sent out.
SER def
Appears smooth under microscope (no ribosomes). It’s a series of membranes like the RER.
SER Functions
lipid synthesis, create phospholipids, cholesterol for cell membranes
metal storage - Ca2+, Zn, cobalt, copper
Detoxification - breaks down drugs, alcohol and toxins, which is why the liver cells are abundant with SER.
Golgi apparatus def
The mail service of the cell. The Golgi is composed of membrane-bound sacs called cisternae. The inside space of each sac is called lumen. The cisternae are arranged in a certain way:
The cis face is closer to the nucleus, while the
trans face is closer to the cell membrane.
The medial face is in between the cis and the trans face.
The Golgi is composed of membrane-bound sacs called …
cisternae
in the golgi, The ….. is closer to the nucleus, while the
…… face is closer to the cell membrane.
The …….face is in between the cis and the trans face.
The cis face is closer to the nucleus, while the
trans face is closer to the cell membrane.
The medial face is in between the …. and the …. face.
Golgi Functions:
The Golgi receives proteins from the RER ribosomes. In the Golgi they’re arranged labeled and repacked.
Modifies proteins, changing or adding proteins
Packages exported proteins with vesicle
Sorts proteins
Mitochondria def
Powerhouse. Producing energy known as ATP. The mitochondria grows and reproduces by themselves without instructions from the nucleus. Has its own DNA containing 13 genes, producing its own proteins.
The DNA is circular and self-replicating. Contains ribosomes similar to that of prokaryotes.
Mitochondria Structure
Double membrane
Outer membrane- permeable
Inner membrane- selective permeability with folds called cristae. The folds increase surface area = more space for chemical reactions
Intermembrane area located between outer and inner membranes
Matrix -space within the inner membrane
Mitochondria Functions
Aerobic respiration- Converts glucose into ATP
Apoptosis - programmed cell death mitochondria creates and secretes enzymes that mediate cell self-destruction
Vesicle def
A small phospholipid bubble, aimed to transport molecules such as proteins from the Golgi towards the cell membrane.
Lysosome def
Lyses - break down, Som/soma-body
Small sac with a membrane, containing digestive enzymes.
Has a low pH of 5.
The “digestive system of the cell”. Breaks down molecules.
Proteasome def
a large protein complex in the cytosol responsible for degrading proteins which have been marked for destruction.
Peroxisome def
A small membrane-bound sac containing hydrogen peroxide. Helps eliminate pathogens using free radicals.
Acts as an immune system for the cell.
The cytoskeleton def
Complex network of protein fibers, that determine the shape, strength, rigidity and cell movement.
It is also the highway ofthe cells, a support and communication system in the cell.
the 3 cytoskeleton fibers:
Microtubules
intermediate filaments
microfilaments
Microtubules structure
25 nanometers.
A hollow tube protein of two subunits: alpha tubulin, beta tubulin.
The tubulin are paired as dimers. They can elongate and disassemble by adding or retracting dimers.
Microtubules functions
Intracellular (inside the cell) transportation
formation of mitotic spindle (takes part and cell division)
formation of cilia - hair like structure on cells, and flagella
Microfilaments structure
Thin filaments- 7 nanometers.
Made of two Twisted chains of proteins called actin.
Microfilaments functions
involved in muscle contraction
provides support, shape, structure to the cell
ring structure - divides the cell into two during mitosis.
Intermediate filaments structure
Medium thickness - 10 to 12 nanometers in size.
creates strong fibers like collagen, keratin.
Intermediate filaments Functions
Intercellular communication (between cells)
Provides structural stability and rigidity of the cell wall
