Cells Flashcards
What are some membrane-bound organelles?
nucleus, mitochondria, ER, golgi, lysosomes
What are some nonmembrane bound organelles?
ribosomes, centrosomes, basal bodies
What are some other names for the cell membrane?
plasma membrane
plasmalemma
What does the phospholipid bilayer consist of?
Phospholipid (amphiphilic)
Cholesterol
Membrane proteins (transmembrane and perpheral)
Carbohydrate molecules (glycocalyx)
What is special about transport through the plasma membrane?
The membrane is selectively permeable: small nonpolar molecules pass through easily and larger polar molecules and charged molecules need help passing through
What are some transport mechanisms through the plasmalemma?
Simple diffusion
Facilitated diffusion
Active transport
Endocytosis (phagocytosis and pinocytosis)
Exocytosis
What is the cytosol primarily made up of?
75-90% water
What are the three fibers of the cytoskeleton? Describe their composition and function.
Microfilaments (7nm diameter): made of actin protein filaments in a helix, form the terminal web internal to the cell membrane
Intermediate filaments(8-10 nm diameter): variety of proteins, including keratin. Structural role
Microtubules (25 nm diameter, 15 nm lumen): tubulin protein forms hollow tubes, cilia and centrioles
Describe the types and functions of the 4 different cellular projections.
Microvilli: short and fingerlike extensions of plasma membrane. increase surface area, good for absorption, nonmotile and supported by microfilaments
Sterocilia: related to microvilli but are a lot longer. Nonmotile, increase SA. Can have a sensory function
Cilia: way longer than microvilli, 9x2 + 2 internal structure pattern of microtubules, mostly motile. Many nonepithelial cells have nonmotile sensory primary-cilium
Falgella: very very long, motile tail of sperm, same microtubule internal structure as cilia
What projections are these?
Brush bored of microvilli
What projections are these?
Epididymis cells with stereocilia
What projections are these?
Respiratory tract with cilia
What is this a picture of?
Mucosa of small intestine
BB = Brush border (microvilli)
CT = Connective tissue
EC = Epithelial cells
L = Lumen
Le = Leukocytes
MC = Mast cell
What is meant by the axoneme in cilia and flagella?
The 9x2 + 2 arrangmenent of the microtubules
Look at this picture and identify the difference between the short microvilli and long cilia that are attached to their dense basal bodies at the apical margin of the cell.
Describe the structure and function of a centriole. then describe a centrosome.
Microtubules arranged as 9 sets of triplets in a circular pattern.
Two centrioles that are arranged perpendicular to one another along with the pericentriolar matrix makes up the centrosome (MTOC)
Centrioles made new microtubules and form the basal bodies of cilia
Important in mitotic spindle formation for cell division.
Describe a mitochondirons structure and function.
Double membrane structure
aerobic respiration, early role in apoptosis
have circular DNA in matrix
What makes up the endomembrane system? What is its structure and function?
ER and golgi makes up endomembrane system.
works to modify, package, and transport lipids and proteins
What is the difference between rough and smooth ER?
Rough ER: studded with ribosomes, continuous with nuclear membrane, cisternae (interconnected flat tubules), makes proteins for cell membrane or lysosomes (cytoplam ribosomes make cytoplasm proteins)
Smooth ER: continuous with rough ER, makes phospholipids and cholesterol for cell membrane, makes steroid hormones. Detox drugs (liver), storage of calcium in muscle
What is the function of the golgi?
Receives products from ER via vesicles and sorts, packages, and tags them to be sent to their destination.
Made of flattened sacs called cisternae
Cis face is convex and receives from ER
Depart from convex trans face
major part of secretory pathway is trans-golgi network of trans face
DOESNT STAIN WITH H&E, but can be seen as pale area near nucleus
What are lysosomes and peroxisomes?
Lysosomes: membrane-bound vesicles that contain digestive hydrolytic enzymes involved in autophagy
Peroxisomes: membrane-bound and contain enzymes in oxidative digestion
What is the largest organelle of the cell?
nucleus
What encloses the nucleus? describe inner and outer membrane. purpose of pores?
nuclear envelope
Inner lacks ribosomes
pores allow communication between nucleoplasm and cytoplasm
What is the nucleolus and its purpose?
this is a cluster of protein, DNA, and RNA that is not bound by a membrane
Site of ribosomal RNA transcription and assembly of ribosomes
MAY HAVE MORE THAN ONE NUCLEOLUS IN A NUCLEUS
What is chromatin? What is the difference between euchromatin and heterochromatin?
Chromatin is DNA wrapped around histones
Euchromatin: more dispersed and lightly stained parts, unpacked and active in transcription
Heterochromatin: highly condensed, not very transcriptionally active
What are the phases of the cell cycle and an approximate amount of time a cell spends in each phase? What phase are nondividing cells in?
G1 (11 hours) - replication of organelles and cytoplasm
S (8 hours) - DNA replication
G2 (4 hours) - growth, protein synthesis
Mitosis (1 hour)
Nondividing cells are in G0 phase
Do embryonic cells have G1 and G2 phases?
NO
Describe prophase.
chromosomes condense
centrioles migrate to poles
nuclear envelope disappears
Describe metaphase.
chromosomes align along metaphase plate
describe the structure and function of the microtubule organizing center (MTOC). What is the kinetochore?
assembles around centrioles
region where most microtubules form
serves as mitotic spindle poles
Kinetochore is where the spindle attaches to the centromere region of the chromosome
Describe anaphase.
chromosomes migrate apart
cleavage furrow begins to form
Describe telophase.
Chromosomes decondense
nucleolus reappears
nuclear envelope reforms
mitotic spindle breaks down
What is cytokinesis?
cleavage furrow completely divides daughter cells
What is meiosis restricted to?
germ cells
Left image:
A = Anaphase
C = Centrioles
Ch = Chromosomes
M = Equatorial plate
of cell in Metaphase
Arrow = Chromosomes
Arrowheads = Cells in
Anaphase
Right image:
Ch = Chromosomes
Arrow = Spindle
apparatus of cell in
Early Telophase
Arrowheads =
Cleavage furrow
Ac = Acini
GC = Goblet cell
N = Nucleus
ZG = Zymogen granules
Arrow = Lateral cell membrane
What should you look at first when identifying a cell? 3 things.
plasma membrane
nucleus
cytoplasm
Things to remember?
cells dont exist in isolation
2D representation of 3D
