Chapter 2 cells Flashcards
Cytology:
Study of cells
Types of microscopy
Light Microscopy
Transmission electron
scanning electron
Light Microscopy
Transmission electron Microscopy
Scanning electron Microscopy
Visible light passes through cell
beam of electrons pass through thin slice of specimen - 2D
beam of electrons bounces off surface of cell - 3D
Which microscopy produces 3-D image?
Scanning electron
Cellular functions (8)
covering lining storage movement connection defense communication reproduction
Cellular functions
lining
epithelial cells in small intestine. regulate nutrient movement into body tissues
Cellular functions
covering
epidermal cells of skin. protect outer surface
Cellular functions
connection
collagen fibers. form ligaments that attach bone-bone
Cellular functions
defense
lymphocytes
produce antibodies to target antigens
Cellular functions
storage
adipocytes
store lipid reserves
Cellular functions
communication
neurons
Cellular functions
movement
skeletal muscles
move skeleton
Cellular functions
reproduction
bone marrow and sperm/oocytes
produce new blood cells and individuals
Most human cells have three basic parts:
plasma membrane
cytoplasm
nucleus
Plasma membrane
aka cell membrane
extremely thin, outer border of cell
selective barrier - regulates passage of gases, nutrients, and waste
Plasma membrane
three parts
polar head of phospholipid molecule
phospholipid bilayer containing proteins
nonpolar tails of phospholipid molecule
Functions of plasma membrane (4)
communication (receptors that recognize and respond to molecular signals)
intercellular connections (flexible boundary, protects cell contents, and supports structure)
physical barrier (phospholipid bilayer separates substances in/outside)
selective permeability (regulates entry/exit)
What is the plasma membrane composed of?
lipids and proteins
Lipids of membrane (3)
proteins of membrane (2)
Phospholipids
cholesterol
glycoplipids
integral
peripheral
Phospholipids
it is the…
each one has?
what do they do in water?
most common lipid in plasma membranes
each has charged head and two uncharged tails
in water, they spontaneously form a bilayer - 2 parallel sheets of phospholipids lying tail to tail.
polar exposed to water with tails facing each other
cholesterol
__ of all membrane lipids
what does it do?
20%
strengthens and stabilizes membrane against extreme temps
glycoplipids
___ -____ of all membrane lipids
what does it have?
5-10%
have carbohydrate groups attached (sugar groups face outward)
Membrane proteins
- what are proteins?
- responsible for___
- two types of membrane proteins
proteins are complex molecules made of amino acid chains
responsible for most membrane functions
integral (embedded) and peripheral (not embedded)
integral proteins
embedded in ____
span ____
can have___
have many___
embedded in phopholipid bilayer
span entire thickness of membrane (called “transmembrane” and are exposed to inside and outside of cell)
can have carbohydrates (sugars) attached to outer surface = glycoproteins.
many varied functions
___ + ____ form the glycocalyx on external surface of plasma membrane
glycoproteins and glycoplipids
Peripheral proteins
not what?
attached where?
not embedded in lipid bilayer
loosely attached to external or internal surface of plasma membrane
many varied functions
Protein-Specific Functions of Plasma Membrane
Transport Intercellular connection Anchorage for the cytoskeleton Enzyme (catalytic) activity Cell–cell recognition Signal transduction
Transport Across the Plasma Membrane
membrane permeability is influences by several factors (6)
Transport proteins Plasma membrane structure Concentration gradient Ionic charge Lipid solubility Molecular size
Transport Across the Plasma Membrane
2 general types of membrane transport
passive and active
Passive transport
does not___
materials move___
__ and ____
does not require cellular energy
materials move down their concentration gradient
diffusion and filtration
active transport
requires:
materials are:
___ and ____
requires energy (ATP) from the cell
materials are moved against their concentration gradients or in large quantities
pumping and bulk transport
Passive transport
includes:
simple diffusion
osmosis
facilitated diffusion
bulk filtration
simple diffusion
small, nonpolar molecules move down concentration gradient
osmosis
diffusion of water
facilitated diffusion
transport proteins help move molecules across membrane
bulk filtration
hydrostatic pressure pushes substances across membrane.
liquids (solvents) and dissolved molecules (solutes) are transported.
Active transport
requires?
includes?
requires energy in form of ATP
includes ion pumps pushing ions against their concentration gradients
also includes bulk transport
active transport pump example
sodium potassium pump
bulk transport
what does it do?
includes?
bulk transport moves large molecules or bulk structures across a plasma membrane
exocytosis and endocytosis
exocytosis
materials packages into vesicles and secreted out of cell when vesicles fuse with plasma membrane
Endocytosis
materials are taken into the cell, packaged into vesicles,
Three forms of endocytosis
Phagocytosis
pinocytosis
receptor-mediated endocytosis
Phagocytosis
nonspecific uptake of particles by formation of membrane extensions (pseudopodia) that surround and engulf particles
Pinocytosis
nonspecific uptake of extracellular fluid
Receptor-mediated endocytosis
engulfing of specific molecules bound to receptors on the plasma membrane
Cytoplasm
includes all materials between __ and ___
1.
2.
3.
plasma membrane and nucleus
cytosol
inclusions
organelles
Cytosol
a __ __ containing __ and many dissolved substances such as:
- - - - - -
A viscous fluid containing water and many dissolved substances, such as: Ions Nutrients Proteins Carbohydrates Lipids Other small molecules
inclusions
are chemical such as:
Some cells store inclusions in their cytosol
Inclusions are chemicals such as:
- Pigments (e.g., melanin in skin cells)
- Nutrient stores (e.g., glycogen in muscle cells; triglycerides in fat cells)
- Protein crystals
organelles
two types
membrane bound and non
membrane bound organelles
endoplasmic reticulum golgi lysosomes peroxisomes mitochondria
non-membrane bound organelles
ribosomes cytoskeleton centrosomes centrioles cilia flagella microvilli
endoplasmic reticulum
what is it?
two types?
network of intracellular membrane bound organelles
enclosed spaces are cisternae
smooth and rough
Smooth ER
What is it?
functions?
smooth due to lack of ribosomes
continuous with rough ER
it performs synthesis, transport, storage of lipids; metabolism of carbs; detox of drugs, alcohol and poison
Rough ER
why is it rough?
RER receives ____ from ribosome
rough because of attachment of ribisomes outside membrane
RER receives newly synthesized proteins from ribosome
-proteins will be secreted, inserted into plasma membrane or included in lysosome
RER modifies __ and __ them into transport vesicles
modifies the proteins and packages them into transport vesicles
Cells that perform lots of ___ have lots of RER and extensive golgi
secretion (pancreas cells)
Golgi Apparatus
what does it do?
stacked cisternae’s lateral edges …
receives material from ER for modification, sorting, and packaging
Stacked cisternae’s lateral edges bulge, pinch off, and give rise to small transport and secretory vesicles
- -Receiving region is the cis-face
- -Shipping region is the trans-face
Functions of Golgi
- modification- modifies new proteins
- packaging - packages enzymes
- sorting - sorts all materials for lysosomes
- __ ___synthesizes protein that is released in a transport vesicle.
- Vesicle from the rough ER moves to the __ ___
- Vesicle fuses with __ __at the receiving region.
- ___ are modifies as they move through Golgi apparatus (e.g., addition of carbohydrate).
- __ __ are packaged and released within secretory vesicle from the shipping region.
- Secretory vesicle merge with the __ ___ to insert molecules into the plasma membrane. or release contents by __. They may also serve as ___.
- Rough ER
- golgi
- golgi
- proteins
- modified proteins
- plasma membrane
exocytosis
lysosomes
Protein flow through golgi
- Proteins synthesized in __ packaged into transport vesicles
- Transport vesicles pinch off from RER and fuse with _____
- Proteins move between and are modified in the ___
- Modified proteins are packaged in___
- Secretory vesicles either undergo __, __, or ___
- RER
- receiving face of Golgi apparatus
- cisternae of Golgi apparatu
- cisternae of Golgi apparatus
- exocytosis, become parts of plasma membrane, or become lysosomes
lysosomes
-Vesicles generated by ___
Contain enzymes used to ____
When a cell is dying it release ___ that digest the cell (autolysis)
- Vesicles generated by Golgi apparatus
- Contain enzymes used to digest and remove waste products and damaged organelles within the cell (autophagy)
- When a cell is dying it releases lysosomal enzymes that digest the cell (autolysis)
Functions of lysosomes
3
- Digestion: Digest all materials that enter cell by endocytosis
- Removal: Remove worn-out/damaged organelles and cellular components; recycle small molecules for resynthesis
- Self-destruction: Digest the remains after cellular death
Peroxisomes
Sacs formed by ___
___ than lysosomes
Use O_2 and catalase to ___
Abundant in __ cells
Sacs formed by pinching off from RER
Smaller than lysosomes
Use O_2 and catalase to detoxify harmful molecules in cell
Abundant in liver cells
Mitochondria
Function to produce __
Cells that require more energy (e.g., muscle cells) have ____
Function to produce ATP
Cells that require more energy (e.g., muscle cells) have more mitochondria
function of mitochondria
energy synthesis - produce ATP by cellular respiration. the powerhouse
Ribosomes
- Comprised of a __ and __
- Responsible for ___
- Free ribosomes float in the ___
- Fixed ribosomes are attached to ___
Comprised of a large and small subunit
Responsible for protein synthesis
Free ribosomes float in the cytosol
Fixed ribosomes are attached to RER
Cytoskeleton
- Proteins organized in the cytosol as __ or ___
- Three cytoskeletal components:
Proteins organized in the cytosol as solid filaments or hollow tubes
Three cytoskeletal components:
Microfilaments
Intermediate filaments
Microtubules
Microfilaments
Composed of __ __intertwined in helical strands
__ and ___ cell shape
Participate in__ and ___
Composed of actin proteins intertwined in helical strands
Maintain and change cell shape
Participate in muscle contraction and cell division
Microtubules
- Composed of tubulin ___
- Radiate from __
- Many functions, including:
Fix __ in place
Maintain cell __ & __
Direct __ of organelles in the cell
Allow cell ___
Move __ during cell division
- Composed of tubulin protein
- Radiate from centrosome
- Many functions, including:
- -Fix organelles in place
- -Maintain cell shape and rigidity
- -Direct movement of organelles in the cell
- -Allow cell motility (in cilia and flagella)
- -Move chromosomes during cell division
Cytoskeleton functions
3
Structural support and organization of cell
Cell division
Movement
Centrosome and Centrioles
Centrosome:
Nonmembranous, spherical structure adjacent to __
Contains pair of ___ at right angles to each other
Centriole:
Nine sets of __ __
Involved in __ microtubules
Attached to chromosomes during cell division causing ___
Centrosome:
Nonmembranous, spherical structure adjacent to nucleus
Contains pair of centrioles at right angles to each other
Centriole:
Nine sets of microtubule triplets
Involved in organizing microtubules
Attached to chromosomes during cell division causing chromosomal migration
Centrosome and Centrioles
functions -2
Microtubule support
Cell division
Cilia and Flagella
Projections from cell containing cytoplasm and microtubules capable of __
Cilia
Flagella
Projections from cell containing cytoplasm and microtubules capable of movement
Cilia
On exposed surfaces of certain cells; move objects across their surface
Flagella
Longer than cilia, and usually singular; used to propel a cell
Microvilli
Tiny projections from __ __
Not capable of ___
Increase surface area for __
Tiny projections from plasma membrane
Not capable of motion
Increase surface area for membrane transport
Nucleus
__ __ for cellular activity
Three main parts:
Control center for cellular activity
Three main parts: nuclear envelope, nucleoli, chromatin
Nucleus functions
2
Cellular regulation: Houses genetic material
Production: Produces ribosomal subunits in nucleolus and exports them into cytoplasm for assembly into ribosomes
Nuclear Envelope
__ __ structure
Controls ____ from nucleus and cytoplasm
Outer membrane is ___
Nuclear pores are __ __channels that allow specific molecules in and out of nucleus
Double membrane structure
Controls entry and exit of molecules from nucleus and cytoplasm
Outer membrane is continuous with endoplasmic reticulum
Nuclear pores are selectively permeable channels that allow specific molecules in and out of nucleus
Nucleoli
- Dark-staining bodies within the __
- Composed of:
- Responsible for making components of small and large units of ___
- Dark-staining bodies within the nucleus
- Composed of RNA, enzymes, and various proteins
- Responsible for making components of small and large units of ribosomes
The nucleus houses ___, a complex molecule containing genetic material
When the cell is not dividing, DNA and associated proteins exist as fine filaments of ___
During cell division chromatin coils tightly to form ___
___ winds around histone proteins to form nucleosomes
The nucleus houses deoxyribonucleic acid (DNA), a complex molecule containing genetic material
When the cell is not dividing, DNA and associated proteins exist as fine filaments of chromatin
During cell division chromatin coils tightly to form chromosomes
DNA winds around histone proteins to form nucleosomes
Life cycle of cell has two phases:
interphase and mitotic phase
interphase
- __ phase
- Normal ___ activities
- May prepare for a future cell ___
time between divisions
- Maintenance (resting) phase
- Normal metabolic activities
- May prepare for a future cell division
mitotic phase
Division produces:
division for growth or cell replacement
Division produces two identical daughter cells
Most cells spend majority of their lives in____
Most cells spend majority of their lives in interphase
Interphase has three stages
G1, S, G2
G1 phase
Cells grow, produce organelles and proteins
Near end of G_1, cells replicate centrioles for future division
Nondividing cells (e.g., neurons) never finish G_1 – they remain arrested in G_0
S phase
“Synthesis” phase where DNA replicates in preparation for cell division
G2 phase
Centriole replication is completed
Organelles and enzymes needed for cell division are produced
Interphase
Synthesis of cellular components needed for ____, including ____
Synthesis of cellular components needed for cell division, including synthesis of DNA.
Mitotic phase
Mitotic phase produces two ____ that are ____ to the original (parent) cell
Two events occur in mitotic phase:
1.
2.
Mitotic phase produces two daughter cells that are genetically identical to the original (parent) cell
Two events occur in mitotic phase:
- Mitosis: Division of the nucleus
- Cytokinesis: Division of the cytoplasm
what are the mitosis stages?
prophase
metaphase
anaphase
telophase
prophase
- Chromatin supercoils forming ___
- Duplicate, identical sister chromatids are joined at ____
- Elongated microtubules called ___ grow from each centriole
- The end of prophase is marked by ____
- Chromatin supercoils forming chromosomes
- Duplicate, identical sister chromatids are joined at centromere
- Elongated microtubules called spindle fibers grow from each centriole
- The end of prophase is marked by dissolution of nuclear envelope
prophase cont’d
- Replicated chromosomes appear due to ____
- ____ breaks down.
- _____ begin to form from centrioles.
- Centrioles move toward ___.
- _____ breaks down at the end of this stage.
- Replicated chromosomes appear due to coiling of chromatin.
- Nucleolus breaks down.
- Spindle fibers begin to form from centrioles.
- Centrioles move toward opposing cell poles.
- Nuclear envelope breaks down at the end of this stage.
metaphase
- Chromosomes…
- ____ attach to centromeres of chromosomes, and form an oval structure called the ____
- Chromosomes line up along equatorial plate
- Spindle fibers attach to centromeres of chromosomes, and form an oval structure called the mitotic spindle
metaphase
- Spindle fibers attach to the centromeres of the chromosomes extending from the ___.
- Replicated chromosomes are ____ of the cell by spindle fibers
- Spindle fibers attach to the centromeres of the chromosomes extending from the centrioles.
- Replicated chromosomes are aligned at the equatorial plate of the cell by spindle fibers
anaphase
Spindle fibers pull…
Spindle fibers pull sister chromatids apart to opposite ends of the dividing cell
anaphase
Centromeres that held sisters chromatids together ____; each sister chromatid is now a…
Single chromosomes move toward …
Centromeres that held sisters chromatids together separate; each sister chromatid is now a single chromosome with its own centromere.
Single chromosomes move toward opposite ends of the cell.
telophase
____form around each set of chromosomes
Chromosomes begin to ___ and ____ disappears
____appears as cytoplasm divides
Nuclear envelopes form around each set of chromosomes
Chromosomes begin to uncoil and mitotic spindle disappears
Cleavage furrow (indentation) appears as cytoplasm divides
telophase
Single chromosomes uncoil to form ___.
A ___ reforms within each nucleus.
____ break up and disappear.
New ____ forms around each set of chromosomes.
___ continues as cleavage furrow deepens.
Single chromosomes uncoil to form chromatin.
A nucleolus reforms within each nucleus.
Spindle fibers break up and disappear.
New nuclear envelope forms around each set of chromosomes.
Cytokinesis continues as cleavage furrow deepens.
Cells can die in two general ways:
1.
2.
Necrosis: Irreversible damage via harmful agents or mechanical damage
Apoptosis: Programmed cell death
