Chapter 3: Cell Structure and Functions Flashcards
basic living unit of all organisms
Cell
The simplest organisms consist of ____ cells
single
humans are composed of ___ cells
multiple
4 Cell Structures
- Plasma Membrane
- Nucleus
- Cytoplasm
- Organelles
control center of the cell
Nucleus
specialized structures within the cell that perform specific functions
Organelles
forms the boundary of the cell through which the cell interacts with its environment
Plasma membrane
living material surrounding the nucleus where most activities take place
Cytoplasm
4 Functions of Cell
- Cell Metabolism and Energy
- Synthesis of molecules
- Communication
- Reproduction and inheritance
outermost component of a cell and serves as the boundary between its inside and outside
Cell Membrane
Cell membrane is also known as ___
plasma membrane
Cell membrane encloses the cytoplasm and forms the boundary between: ___ and ____
- intracellular
- extracellular
Cell membrane’s primary role lies in regulating the ____, including nutrients and waste materials
passage of substances
Cell membrane’s structure is described by the ___
fluid-mosaic model
In Phospholipid Structure, phospholipids form a ___
double layer of molecules.
In the phospholipid, the ___ ___ (water-loving) head face the extracellular and intracellular fluids.
polar hydrophilic (water-loving)
head
The nonpolar hydrophobic (water-fearing) tail face away from the ___
fluid, towards the center of the double layer.
Cell membranes are ___ ____, allowing some substances to pass into or out of cells while restricting others.
selectively permeable
Movement through the cell membrane can be either ___ or___
- passive
- active
require the cell to expend energy, usually in the form of ATP
Active Transport Mechanisms
Active Transport Mechanisms includes
(1) active transport
(2) secondary active transport
(3) endocytosis
(4) exocytosis
do not require the cell to use energy
Passive Transport Mechanisms
Passive Transport Mechanisms includes
(1) diffusion
(2) osmosis
(3) facilitated diffusion
process where solutes, such as ions or molecules, move from an area of higher concentration to an area of lower concentration.
Diffusion
Diffusion generally involves the movement of substances in a solution down a ___ ___
concentration gradient
a difference in solute concentration between two points divided by the distance between them.
Concentration Gradient
acts as a barrier to most water-soluble substances
phospholipid bilayer
2 Cell Membrane Channels
- Leak Channels
- Gated Channels
open and close to limit the movement of ions across the membrane
Gated Channels
constantly allow ions to pass through
Leak Channels
diffusion of water across a selectively permeable membrane, such as the cell membrane, from a region of higher water concentration to one of lower water concentration.
Osmosis
force required to prevent water movement across a selectively permeable membrane.
Osmotic Pressure
pushing force on water due to the presence of more fluid in one region than another.
Hydrostatic Pressure
A cell may be placed in solutions that are either:
- hypotonic
- isotonic
- hypertonic
equal solute and water concentration
Isotonic
lower solute concentration, higher water concentration
Hypotonic
higher solute concentration, lower water concentration
Hypertonic
transport of molecules from the region of higher concentration to the region of lower concentration with the help of carriers.
Facilitated Diffusion
Exhibits the properties of specificity, competition, and saturation.
Carrier-Mediated Transport
3 Types of Carrier-Mediated Transport
- Facilitated Diffusion
- Active Transport
- Secondary Active Transport
___ ____ does not require ATP for energy
Facilitated Diffusion
__ ___ does require ATP for transport.
Active Transport
- carrier-mediated process, requiring ATP, that moves substances across the cell membrane from regions of lower concentration to those of higher concentration against a concentration gradient.
- can move substances from lower concentration
Active Transport
uses the energy provided by a concentration gradient established by the active transport of one substance, such as Na+ to transport other substances.
Secondary Active Transport
2 Types of Secondary Active Transport
- Contransport
- Countertransport
process that that brings materials into cell using vesicles.
Endocytosis
3 Types of Endocytosis
- Receptor-mediated endocytosis
- Phagocytosis
- Pinocytosis
occurs when a specific substance binds to the receptor molecule and is transported into the cell.
Receptor-mediated endocytosis
often used for endocytosis when solid particles are ingested.
Phagocytosis
has much smaller vesicles formed, and they contain liquid rather than solid particles.
Pinocytosis
membrane-bound sacs
secretory vesicles
involves the use of membrane-bound sacs called secretory vesicles that accumulate materials for release from the cell.
Exocytosis
Examples of exocytosis
secretion of digestive enzymes
organelles of the cell:
- nucleus
- ribosomes
- endoplasmic reticulum
- golgi apparatus
- secretory vesicle
- lysosomes
- peroxisomes
- mitochondria
- cytoskeleton
- centriole
- large organelle located near the center of the cell
- Site of RNA synthesis and ribosomal subunit assembly.
Nucleus
The nucleus is bounded by a ___ ___ , which consists of outer and inner membranes with a narrow space between them.
Nuclear Envelope
where materials can pass into or out of the nucleus.
Nuclear pores
a loosely coiled chromosome that becomes tightly coiled
during cell division.
Chromatin
diffuse bodies with no surrounding membrane found within the nucleus where subunits of ribosomes are formed.
Nucleoli
made of both RNA and protein and are the site of protein synthesis in the cell.
Ribosomes
not attached to any organelle and synthesize proteins used inside the cell.
Free Ribosomes
produce integral membrane proteins and proteins that are secreted from the cell.
Ribosomes attached to ER
A series of membranes forming sacs and tubules that extend from the outer nuclear membrane into the cytoplasm.
Endoplasmic Reticulum
attached with ribosomes, the sites where proteins are produced.
Rough Endoplasmic Reticulum
has no attached ribosomes and is a site for lipid synthesis, and cellular detoxification.
Smooth Endoplasmic Reticulum
process by which enzymes act on chemicals and drugs to change their structure and reduce their toxicity.
Detoxification
- consists of closely packed stacks of curved, membrane-bound sacs
- packing and distribution center that collects, modifies, packages, and distributes proteins and lipids manufactured by the ER
Golgi Apparatus
Golgi Apparatus is also known as
Golgi complex
small, membrane-bound sac that transports or stores materials within cells.
Secretory vesicles
membrane-bound vesicles formed from the Golgi apparatus and contain a variety of enzymes that function as intracellular digestive systems.
Lysosomes
membrane-bound vesicles that are smaller than lysosomes and contain enzymes that break down fatty acids and amino acids that produce hydrogen peroxide (H2O2) as a toxic by-product.
Peroxisomes
small organelles responsible for producing considerable amounts of ATP by aerobic (with O2) metabolism.
Mitochondria
numerous folds of the inner membrane
Cristae
The outer membranes have a ____, but the inner membranes have ___ ___
- smooth contour
- numerous folds
internal framework of the cell that supports the cell and holds the nucleus and other organelles in place.
Cytoskeleton
hollow structures formed from protein units called tubulin and it is vital for cell shape, division, and building structures like
cilia.
Microtubules
small fibrils formed from actin protein subunits that structurally support the cytoplasm, determining cell shape.
Microfilaments
fibrils formed from protein subunits that are smaller in diameter than microtubules but larger in diameter than microfilaments and they provide mechanical support/ strength to the cell.
Intermediate filaments
a specialized area of cytoplasm close to the nucleus where microtubule formation occurs and contains two centrioles that facilitate the movement of chromosomes during cell division.
Centrosome
cylindrical structures composed of microtubules that project from the surface of cells and are responsible for the movement of materials over the top of cells, such as mucus.
Cilia
have a structure similar to that of cilia but are much longer, and they usually occur only one per cell.
Flagella
specialized extensions of the cell membrane that are supported by microfilaments and increase the surface area of the cell but don’t actively move like cilia and flagella do.
Microvilli
“to carry out vital functions and necessary metabolic processes essential for the proper functioning of the cell and/or organism.”
Cell Activity
determined by the type of proteins produced
cell characteristics
the cells that make up the human body are formed through _____
cell division and cell differentiation
____ contains the information that directs protein synthesis, this process is called __ ___
- DNA
- gene expression
a sequence of nucleotides that provides a chemical set of instructions for making a specific protein
gene
Two Steps of Gene Expression
- Transcription
- Translation
Takes place in the nucleus of the cells and DNA determines the structure of mRNA through it
Transcriptions
Organic Bases of DNA
- Thymine
- Adenine
- Guanine
- Cytosine
mRNA contains:
- Uracil
- Adenine
- Cytosine
- Guanine
synthesis of proteins based on the information in the mRNA and occurs in the cell cytoplasm after mRNA has exited the nucleus through the nuclear pores to the ribosomes.
Translation
Two Major Phases of Cell Cycle
- Interphase
- Mitosis
Each human cells, except sex cells, contains __ chromosomes.
46 chromosomes
involves formation of 2 daughter cells from a single parent cell.
Mitosis
Mitosis is divided into 4 Phases:
- Prophase
- Metaphase
- Anaphase
- Telophase
Chromatin condenses to form visible chromosomes.
Prophase
Chromosomes align near the center of the cells
Metaphase
Chromatids separate at the beginning of ___
Anaphase
The chromosomes begin to unravel and resemble the genetic material during interphase
Telophase
Two Types of Tumor
- Benign
- Malignant
Less dangerous type of tumor which they are not inclined to spread but still increase in size.
Benign Tumor
Can be spread by local growth and expansion or by metastasis
Malignant Tumor
refers to malignant and lack the normal growth control that is exhibited by most adult tissue
Cancer
process by which cells develop with specialized structures and functions
Differentiation
- normal process by which cell numbers within various tissues are adjusted and controlled
- regulated by specific genes
Apoptosis
