Cell Structure Flashcards
Specialized structures in cells that perform specific functions
Organelles
Examples of Organelles
Nucleus
Mitochondria
Ribosomes
Jelly-like substance that holds organelles
Cytoplasm
A structure that encloses the cytoplasm
Cell membrane / plasma membrane
Functions of the Cell
Smallest units of life Cell metabolism and energy use Synthesis of molecules Communication Reproduction and inheritance
The outermost component of a cell.
Cell membrane / plasma membrane
It forms a boundary between material inside the cell and the outside.
Cell membrane / plasma membrane
It acts as a selective barrier.
Cell membrane / plasma membrane
Materials inside the cell are
Intracellular
Materials outside the cell are
Extracellular
Model used to describe the cell membrane structure.
Fluid-mosaic model
What does the cell membrane contains
Phospholipids
Cholesterol
Proteins
Carbohydrates.
Form a bilayer.
Phospholipids
Phospholipids contain 2 regions
Polar and Nonpolar
A phospholipid molecule has a polar head region that is
Hydrophilic
This region is exposed to water around the membrane.
Polar Region
This region is facing the interior of the membrane.
Nonpolar Region
A phospholipid molecule has a nonpolar tail region that is
Hydrophobic
Polar head region contains
Phosphate
Nonpolar tail region contains
Fatty acids
Cell membrane is made up of 2 major types of molecules
Phospholipids and Proteins
Add strength and stability by limiting movement of phospholipids
Cholesterol
What are the proteins that float among the phospholipids or extend from inner to outer surface of the membrane
Membrane channels Carrier molecules Receptor molecules Enzymes Structural supports
The cell membrane has ___________, which allows only certain substances to pass in and out of the cell.
Selective permeability
Substances such as these are found in higher concentrations inside the cell.
Enzymes, glycogen, and potassium
Substances such as these are found in higher concentrations outside the cell.
Sodium, calcium, and chloride
Some substances, like ____________ can pass directly through the cell membrane’s phospholipid bilayer.
O2 and CO2
Some substances must pass through transmembrane protein channels, such as ____ through its channels.
Na+
True or False
The route of transport through the membrane depends on the size, shape, and charge of the substance.
True
Some substances require carrier molecules to transport them across the cell membrane, such as _______.
Glucose
True or False
All substances require a vesicular transport across the membrane.
False
Some, just some
True or False
The vesicle must fuse with the cell membrane for transport.
True
This transport does not require the cell to expend energy.
Passive membrane transport
This transport require the cell to expend energy, usually in the form of ATP.
Active membrane transport
Passive membrane transport mechanisms include _____________________________.
Diffusion, osmosis, and facilitated diffusion
Active membrane transport mechanisms include _____________________________.
Active transport, secondary active transport, endocytosis, and exocytosis
Generally involves movement of substances in a solution down a concentration gradient.
Diffusion
A solution is generally composed of two major parts, ______________.
Solutes and solvent
________ are substances dissolved in a predominant liquid or gas, which is called the solvent.
Solutes
Solutes are substances dissolved in a predominant liquid or gas, which is called the __________.
Solvent
True or False
Solutes, such as ions or molecules, tend to move from an area of higher concentration of a solute to an area of lower concentration of that same solute in solution.
True
This movement from high concentration to a low concentration is _____________.
Diffusion
A ________________ is the difference in the concentration of a solute in a solvent between two points divided by the distance between the two points.
Concentration gradient
True or False
The concentration gradient is said to be steeper when the concentration difference is large and/or the distance is bigger.
False
CG is steeper when
- Concentration difference is large
- Distance is smaller
_____________ can diffuse directly through the phospholipid bilayer.
Lipid soluble substances
________________, such as ions, can diffuse across the cell membrane only by passing through cell membrane channels.
Water-soluble substances
Two classes of cell membrane channels
Leak channels and gated channels.
Constantly allow ions to pass through.
Leak channels
Limit the movement of ions across the membrane by opening and closing.
Gated channels
Is the diffusion of water (a solvent) across a selectively permeable membrane from a region of higher water concentration to one of lower water concentration.
Osmosis
The force required to prevent movement of water across cell membrane
Osmotic pressure
True or False
Osmotic pressure depends on the difference of solution concentrations inside a cell relative to outside the cell.
True
A cell may be placed in solutions that are either _______________________ compared to the cell cytoplasm.
Hypotonic, isotonic, or hypertonic
A ________ solution has a lower concentration of solutes and a higher concentration of water relative to the cytoplasm of the cell.
Hypotonic
The solution has less tone, or osmotic pressure, than the cell.
Hypotonic
Water moves by osmosis into the cell, causing it to swell.
Hypotonic
If the cell swells enough, it can rupture, a process called _______.
Lysis
A cell immersed in an _______ solution has the same solute concentrations inside and outside the cell.
Isotonic
The cell will neither shrink nor swell.
Isotonic
The cytoplasm of a cell in a ________ solution has a lower solute concentration and higher water concentration than the surrounding solution.
Hypertonic
Water moves by osmosis from the cell into the hypertonic solution resulting in cell shrinkage.
Hypertonic
Cell shrinkage
Crenation
True or False
Some water-soluble, electrically charged or large sized particles cannot enter or leave through the cell membrane by diffusion.
True
True or False
Substances such as amino acids, glucose, and some polar molecules produced by the cell are lipid-soluble
False
Water soluble
Proteins within the cell membrane involved in carrier-mediated transport.
Carrier molecules
Carrier-mediated transport mechanisms include
Facilitated diffusion and Active transport
Carrier-mediated transport that does not require ATP for energy.
Facilitated diffusion
Carrier-mediated transport that require ATP for transport.
Active transport
Is a carrier-mediated transport process that moves substances across the cell membrane from an area of higher concentration to an area of lower concentration of that substance.
Facilitated diffusion
True or False
Because active transport’s movement is with the concentration gradient, metabolic energy in the form of ATP is not required.
False
Facilitated diffusion
Is a 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.
Active transport
Moves Na+ out of cells and K+ into cells.
The result is a higher concentration of Na+ outside cells and a higher concentration of K+ inside cells.
Sodium-potassium pump
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
The diffusing substance moves in the same direction as the initial active transported substance.
Cotransport
The diffusing substance moves in a direction opposite to that of the initial active transported substance.
Countertransport
Is a process that brings materials into cell using vesicles.
Endocytosis
Occurs when a specific substance binds to the receptor molecule and is transported into the cell.
Receptor-mediated endocytosis
Is often used for endocytosis when solid particles are ingested.
Phagocytosis
Has much smaller vesicles formed, and they contain liquid rather than solid particles.
Pinocytosis
Involves the use of membrane-bound sacs called secretory vesicles that accumulate materials for release from the cell.
Exocytosis
The vesicles move to the cell membrane and fuse, ultimately releasing the material by __________.
Exocytosis
Secretion of digestive enzymes is an example of
Exocytosis
Membrane-bound sacs that accumulate materials for release from the cell.
Secretory vesicles
Is a large organelle usually located near the center of the cell.
Nucleus
The nucleus is bounded by a______________, which consists of outer and inner membranes with a narrow space between them.
Nuclear envelope
The nuclear membrane contains _____________-, through which materials can pass into or out of the nucleus.
Nuclear pores
The nuclei of human cells contain __ pairs of chromosomes which consist of DNA and proteins.
23 pairs
During most of a cell’s life, the chromosomes are loosely coiled and collectively called __________.
Chromatin
True or False
When a cell prepares to divide, the chromosomes become tightly coiled and are visible when viewed with a microscope.
True
Within the nucleus are_________, which are diffused bodies with no surrounding membrane that are found within the nucleus
Nucleoli
True or False
There are usually only one nucleoli within the nucleus.
False
One to several nucleoli
Ribosomes, a type of cytoplasmic organelle, are formed within a _________.
Nucleolus
These ribosomal components exit the nucleus through the _________.
Nuclear pores
Are produced in the nucleolus.
Ribosome
Organelles where proteins are produced.
Ribosomes
Ribosomes may be attached to other organelles, such as the _________________.
Endoplasmic reticulum
Ribosomes that are not attached to any other organelle are called
Free ribosomes
Is a series of membranes forming sacs and tubules that extends from the outer nuclear membrane into the cytoplasm.
Endoplasmic reticulum
Is involved in protein synthesis and is rough due to attached ribosomes.
Rough ER
Is a site for lipid synthesis, cellular detoxification, and it stores calcium ions in skeletal muscle cells.
Smooth ER
Consists of closely packed stacks of curved, membrane-bound sacs.
Golgi apparatus / Golgi complex / Golgi body
It collects, modifies, packages, and distributes proteins and lipids manufactured by the ER.
Golgi apparatus / Golgi complex / Golgi body
Forms vesicles, some of which are secretory vesicles, lysosomes, and other vesicles.
Golgi apparatus / Golgi complex / Golgi body
Are membrane-bound vesicles formed from the Golgi apparatus.
Lysosomes
They contain a variety of enzymes that function as intracellular digestive systems.
Lysosomes
Vesicles formed by endocytosis may fuse with _____________ in order to breakdown materials in the endocytotic vesicles.
Lysosomes
Example of a vesicle fusing with a lysosome
White blood cells phagocytizing bacteria.
Are small, membrane-bound vesicles containing enzymes that break down fatty acids, amino acids, and hydrogen peroxide (H2O2).
Peroxisomes
Is a by-product of fatty acid and amino acid breakdown and can be toxic to a cell.
Hydrogen peroxide
The enzymes in _________ break down hydrogen.
Peroxisomes
Are small organelles responsible for producing considerable amounts of ATP by aerobic (with O2) metabolism.
Mitochondria (singular mitochondrion)
They have inner and outer membranes separated by a space.
Mitochondria (singular mitochondrion)
Mitochondria have outer membranes with a smooth contour, but the inner membranes have numerous folds, called ______, which project into the interior of the mitochondria.
cristae
The material within the inner membrane is the ___________ and contains enzymes and mitochondrial DNA (mtDNA).
Mitochondrial matrix
True or False
Cells with a large energy requirement have more mitochondria than cells that require less energy.
True
Gives internal framework to the cell.
Cytoskeleton
It consists of protein structures that support the cell, hold organelles in place, and enable the cell to change shape.
Cytoskeleton
Protein structures found in cytoskeletons
Microtubules, microfilaments, and intermediate filaments.
Hollow structures formed from protein subunits.
Microtubules
Perform a variety of roles, including helping to support the cytoplasm of cells, assisting in cell division, and forming essential components of certain organelles, such as cilia and flagella.
Microtubules
Small fibrils formed from protein subunits that structurally support the cytoplasm, determining cell shape.
Microfilaments
Some ________ are involved with cell movement.
Microfilaments
__________ in muscle cells enable the cells to shorten, or contract.
Microfilaments
Are fibrils formed from protein subunits that are smaller in diameter than microtubules but larger in diameter than microfilaments.
Intermediate filaments
They provide mechanical support to the cell.
Intermediate filaments
A specific type of intermediate filament is _____, a protein associated with skin cells.
Keratin
Is a specialized area of cytoplasm close to the nucleus where microtubule formation occurs.
Centrosome
It contains two centrioles, which are normally oriented perpendicular to each other.
Centrosome
Is a small, cylindrical organelle composed of microtubules.
Centriole
Is involved in the process of mitosis.
Centriole
Cylindrical structures that extend from the cell and are composed of microtubules.
Cilia
They 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
An example of a cell that has a flagella
Sperm cells each have one flagellum, which propels the sperm cell.
Are specialized extensions of the cell membrane that are supported by microfilaments.
Microvilli
They do not actively move as cilia and flagella do.
Microvilli
Are numerous on cells that have them and they increase the surface area of those cells.
Microvilli
They are abundant on the surface of cells that line the intestine, kidney, and other areas in which absorption is an important function.
Microvilli
Identity of a cell are determined by these
A cell’s characteristics are determine by the type of proteins produced.
The proteins produced are in turn determined by the genetic information in the nucleus.
Information in DNA provides the cell with a code for its cellular processes.
Contains the information that directs protein synthesis;
DNA
A DNA molecule consists of _________ joined together to form two nucleotide strands.
Nucleotides
True or False
The two strand of nucleotides are connected and resemble a ladder that is twisted around its long axis.
True
Each ________ consists of a 5-carbon sugar, a phosphate group, and a nitrogenous base.
Nucleotide
Process where information in our gene is used for protein synthesis
Gene expression
True or False
Each nucleotide on one DNA strand has a specific bonding pattern to another nucleotide on the opposite strand.
True
Is a sequence of nucleotides that provides a chemical set of instructions for making a specific protein.
Gene
Gene expression, which is protein synthesis, involves _____________________.
Transcription and translation
Involves copying DNA into messenger RNA.
Transcription
Involves messenger RNA being used to produce a protein.
Translation
Transcription takes place in the _______ of the cell.
Nucleus
DNA determines the structure of mRNA through _______.
Transcription
During _______, the double strands of a DNA segment separate, and DNA nucleotides of the gene pair with RNA nucleotides that form the mRNA.
Transcription
DNA contains one of the following organic bases:
Thymine, adenine, cytosine, or guanine.
Messenger RNA (mRNA) contains
Uracil, adenine, cytosine, or guanine.
DNA’s thymine pairs with RNA’s _______.
Adenine
True or False
DNA nucleotides pair only with any type of RNA nucleotides.
False
pair up with SPECIFIC type of RNA nucleotides
DNA’s adenine pairs with RNA’s ______.
Uracil
DNA’s cytosine pairs with RNA’s _________
Guanine
DNA’s guanine pairs with RNA’s _______.
Cytosine
Occurs in the cell cytoplasm after mRNA has exited the nucleus through the nuclear pores.
Translation
The mRNA attaches to a ribosome.
Translation
True or False
Codons (3 nucleotide bases) on the mRNA are read by anticodons (3 nucleotide bases) on transfer RNA (tRNA).
True
Transports specific amino acids from the cytoplasm to the ribosome-mRNA complex and initiates formation of the polypeptide chain.
Transfer RNA
During growth and development, __________ occurs to increase the number of cells or replace damaged or dying ones.
Cell division
The cell cycle includes two major phases: a nondividing phase, called _________, and a cell dividing phase, termed _______.
Interphase
Mitosis
During______, the DNA (located in chromosomes in the cell’s nucleus) is replicated.
Interphase
Replication of DNA gives two identical _______ joined at a _________; both form one chromosome.
Chromatids
Centromere
Each human cell (except sperm and egg) contains __ pairs of chromosomes.
23 pairs
The___________ contain 23 chromosomes total.
Sperm or egg cell
Two X chromosomes if the person is
Female
X and Y chromosome if the person is
Male
Involves formation of 2 daughter cells from a single parent cell.
Mitosis
Mitosis is divided into four phases:
Prophase, metaphase, anaphase, and telophase.
The chromatin condenses to form visible chromosomes.
Prophase
Microtubules, termed spindle fibers, form to assist in breaking the centromere between the chromatids and move the chromosomes to opposite sides of the cell.
Prophase
The nuclear membrane dissolves.
Prophase
The chromosomes align near the center of the cell.
Metaphase
The movement of the chromosomes is regulated by the attached spindle fibers.
Metaphase
The chromatids separate and each chromatid is called a chromosome.
Anaphase
Each of the two sets of 46 chromosomes is moved by the spindle fibers toward the centriole at one of the poles of the cell.
Anaphase
Each set of chromosomes has reached an opposite pole of the cell, and the cytoplasm begins to divide.
Anaphase
The chromosomes in each of the daughter cells become organized to form two separate nuclei, one in each newly formed daughter cell.
Telophase
The chromosomes begin to unravel and resemble the genetic material during interphase.
Telophase
Cytoplasm division is completed, and two separate daughter cells are produced.
Telophase
The process by which cells develop with specialized structures and functions is called
Differentiation
Termed programmed cell death, is a normal process by which cell numbers within various tissues are adjusted and controlled.
Apoptosis
True or False
In the developing fetus, apoptosis removes extra tissue, such as cells between the developing fingers and toes.
True
True or False
In some adult tissues, apoptosis eliminates excess cells to maintain a constant number of cells within the tissue.
True
Causes for cellular aging
Existence of a cellular clock Presence of death genes DNA damage Formation of free radicals Mitochondrial damage
Abnormal proliferations of cells.
Tumors
They are due to problems occurring in the cell cycle.
Tumors
Some tumors are ________ and some are (cancer).
Benign
Malignant
Process of the spread of malignant tumors
Metastasis
