Module 3: The Cellular Level of Organization

Lesson 1: The Cell Membrane: Structure

Màng Tế Bào: Cấu Trúc

Nội dung bài học:
Mỗi bài học (lesson) bao gồm 4 phần chính: Thuật ngữ, Luyện Đọc, Luyện Nghe, và Bàn Luận.
Sử dụng tính năng:
Bôi hoặc nhấp đôi vào từ, sau đó ấn vào biểu tượng để tra nghĩa từ đó. Khi bạn đưa chuột đến câu (hoặc khi nhấp vào câu trên màn hình điện thoại), gợi ý về cách hiểu câu đó sẽ hiện lên. Cuối cùng, bạn có thể đánh dấu hoàn thành toàn bộ bài học bằng cách ấn vào nút “Hoàn Thành” ở cuối trang.
Đăng ký và đăng nhập
Bạn cần đăng ký và đăng nhập vào tài khoản để lưu quá trình học.
Xem hướng dẫn đầy đủ
Dưới đây là danh sách những thuật ngữ Y khoa của module The Cellular Level of Organization.
Khái quát được số lượng thuật ngữ sẽ xuất hiện trong bài đọc và nghe sẽ giúp bạn thoải mái tiêu thụ nội dung hơn. Sau khi hoàn thành nội dung đọc và nghe, bạn hãy quay lại đây và luyện tập (practice) để quen dần các thuật ngữ này. Đừng ép bản thân phải nhớ các thuật ngữ này vội vì bạn sẽ gặp và ôn lại danh sách này trong những bài học (lesson) khác của cùng một module.

Medical Terminology: The Cellular Level of Organization

active transport
form of transport across the cell membrane that requires input of cellular energy
amphipathic
describes a molecule that exhibits a difference in polarity between its two ends, resulting in a difference in water solubility
anaphase
third stage of mitosis (and meiosis), during which sister chromatids separate into two new nuclear regions of a dividing cell
anticodon
consecutive sequence of three nucleotides on a tRNA molecule that is complementary to a specific codon on an mRNA molecule
autolysis
breakdown of cells by their own enzymatic action
autophagy
lysosomal breakdown of a cell’s own components
cell cycle
life cycle of a single cell, from its birth until its division into two new daughter cells
cell membrane
membrane surrounding all animal cells, composed of a lipid bilayer interspersed with various molecules; also known as plasma membrane
centriole
small, self-replicating organelle that provides the origin for microtubule growth and moves DNA during cell division
centromere
region of attachment for two sister chromatids
centrosome
cellular structure that organizes microtubules during cell division
channel protein
membrane-spanning protein that has an inner pore which allows the passage of one or more substances
checkpoint
progress point in the cell cycle during which certain conditions must be met in order for the cell to proceed to a subsequence phase
chromatin
substance consisting of DNA and associated proteins
chromosome
condensed version of chromatin
cilia
small appendage on certain cells formed by microtubules and modified for movement of materials across the cellular surface
cleavage furrow
contractile ring that forms around a cell during cytokinesis that pinches the cell into two halves
codon
consecutive sequence of three nucleotides on an mRNA molecule that corresponds to a specific amino acid
concentration gradient
difference in the concentration of a substance between two regions
cyclin
one of a group of proteins that function in the progression of the cell cycle
cyclin-dependent kinase (CDK)
one of a group of enzymes associated with cyclins that help them perform their functions
cytokinesis
final stage in cell division, where the cytoplasm divides to form two separate daughter cells
cytoplasm
internal material between the cell membrane and nucleus of a cell, mainly consisting of a water-based fluid called cytosol, within which are all the other organelles and cellular solute and suspended materials
cytoskeleton
“skeleton” of a cell; formed by rod-like proteins that support the cell’s shape and provide, among other functions, locomotive abilities
cytosol
clear, semi-fluid medium of the cytoplasm, made up mostly of water
diffusion
movement of a substance from an area of higher concentration to one of lower concentration
diploid
condition marked by the presence of a double complement of genetic material (two sets of chromosomes, one set inherited from each of two parents)
DNA polymerase
enzyme that functions in adding new nucleotides to a growing strand of DNA during DNA replication
DNA replication
process of duplicating a molecule of DNA
electrical gradient
difference in the electrical charge (potential) between two regions
endocytosis
import of material into the cell by formation of a membrane-bound vesicle
endoplasmic reticulum (ER)
cellular organelle that consists of interconnected membrane-bound tubules, which may or may not be associated with ribosomes (rough type or smooth type, respectively)
exocytosis
export of a substance out of a cell by formation of a membrane-bound vesicle
exon
one of the coding regions of an mRNA molecule that remain after splicing
extracellular fluid (ECF)
fluid exterior to cells; includes the interstitial fluid, blood plasma, and fluid found in other reservoirs in the body
facilitated diffusion
diffusion of a substance with the aid of a membrane protein
flagellum
appendage on certain cells formed by microtubules and modified for movement
G0 phase
phase of the cell cycle, usually entered from the G1 phase; characterized by long or permanent periods where the cell does not move forward into the DNA synthesis phase
G1 phase
first phase of the cell cycle, after a new cell is born
G2 phase
third phase of the cell cycle, after the DNA synthesis phase
gene
functional length of DNA that provides the genetic information necessary to build a protein
gene expression
active interpretation of the information coded in a gene to produce a functional gene product
genome
entire complement of an organism’s DNA; found within virtually every cell
glycocalyx
coating of sugar molecules that surrounds the cell membrane
glycoprotein
protein that has one or more carbohydrates attached
Golgi apparatus
cellular organelle formed by a series of flattened, membrane-bound sacs that functions in protein modification, tagging, packaging, and transport
helicase
enzyme that functions to separate the two DNA strands of a double helix during DNA replication
histone
family of proteins that associate with DNA in the nucleus to form chromatin
homologous
describes two copies of the same chromosome (not identical), one inherited from each parent
hydrophilic
describes a substance or structure attracted to water
hydrophobic
describes a substance or structure repelled by water
hypertonic
describes a solution concentration that is higher than a reference concentration
hypotonic
describes a solution concentration that is lower than a reference concentration
integral protein
membrane-associated protein that spans the entire width of the lipid bilayer
intermediate filament
type of cytoskeletal filament made of keratin, characterized by an intermediate thickness, and playing a role in resisting cellular tension
interphase
entire life cycle of a cell, excluding mitosis
interstitial fluid (IF)
fluid in the small spaces between cells not contained within blood vessels
intracellular fluid (ICF)
fluid in the cytosol of cells
intron
non-coding regions of a pre-mRNA transcript that may be removed during splicing
isotonic
describes a solution concentration that is the same as a reference concentration
kinetochore
region of a centromere where microtubules attach to a pair of sister chromatids
ligand
molecule that binds with specificity to a specific receptor molecule
lysosome
membrane-bound cellular organelle originating from the Golgi apparatus and containing digestive enzymes
messenger RNA (mRNA)
nucleotide molecule that serves as an intermediate in the genetic code between DNA and protein
metaphase
second stage of mitosis (and meiosis), characterized by the linear alignment of sister chromatids in the center of the cell
metaphase plate
linear alignment of sister chromatids in the center of the cell, which takes place during metaphase
microfilament
the thinnest of the cytoskeletal filaments; composed of actin subunits that function in muscle contraction and cellular structural support
microtubule
the thickest of the cytoskeletal filaments, composed of tubulin subunits that function in cellular movement and structural support
mitochondrion
one of the cellular organelles bound by a double lipid bilayer that function primarily in the production of cellular energy (ATP)
mitosis
division of genetic material, during which the cell nucleus breaks down and two new, fully functional, nuclei are formed
mitotic phase
phase of the cell cycle in which a cell undergoes mitosis
mitotic spindle
network of microtubules, originating from centrioles, that arranges and pulls apart chromosomes during mitosis
multipotent
describes the condition of being able to differentiate into different types of cells within a given cell lineage or small number of lineages, such as a red blood cell or white blood cell
mutation
change in the nucleotide sequence in a gene within a cell’s DNA
nuclear envelope
membrane that surrounds the nucleus; consisting of a double lipid-bilayer
nuclear pore
one of the small, protein-lined openings found scattered throughout the nuclear envelope
nucleolus
small region of the nucleus that functions in ribosome synthesis
nucleosome
unit of chromatin consisting of a DNA strand wrapped around histone proteins
nucleus
cell’s central organelle; contains the cell’s DNA
oligopotent
describes the condition of being more specialized than multipotency; the condition of being able to differentiate into one of a few possible cell types
organelle
any of several different types of membrane-enclosed specialized structures in the cell that perform specific functions for the cell
osmosis
diffusion of water molecules down their concentration gradient across a selectively permeable membrane
passive transport
form of transport across the cell membrane that does not require input of cellular energy
peripheral protein
membrane-associated protein that does not span the width of the lipid bilayer, but is attached peripherally to integral proteins, membrane lipids, or other components of the membrane
peroxisome
membrane-bound organelle that contains enzymes primarily responsible for detoxifying harmful substances
phagocytosis
endocytosis of large particles
pinocytosis
endocytosis of fluid
pluripotent
describes the condition of being able to differentiate into a large variety of cell types
polypeptide
chain of amino acids linked by peptide bonds
polyribosome
simultaneous translation of a single mRNA transcript by multiple ribosomes
promoter
region of DNA that signals transcription to begin at that site within the gene
prophase
first stage of mitosis (and meiosis), characterized by breakdown of the nuclear envelope and condensing of the chromatin to form chromosomes
proteome
full complement of proteins produced by a cell (determined by the cell’s specific gene expression)
reactive oxygen species (ROS)
a group of extremely reactive peroxides and oxygen-containing radicals that may contribute to cellular damage
receptor
protein molecule that contains a binding site for another specific molecule (called a ligand)
receptor-mediated endocytosis
endocytosis of ligands attached to membrane-bound receptors
ribosomal RNA (rRNA)
RNA that makes up the subunits of a ribosome
ribosome
cellular organelle that functions in protein synthesis
RNA polymerase
enzyme that unwinds DNA and then adds new nucleotides to a growing strand of RNA for the transcription phase of protein synthesis
S phase
stage of the cell cycle during which DNA replication occurs
selective permeability
feature of any barrier that allows certain substances to cross but excludes others
sister chromatid
one of a pair of identical chromosomes, formed during DNA replication
sodium-potassium pump
(also, Na+/K+ ATP-ase) membrane-embedded protein pump that uses ATP to move Na+ out of a cell and K+ into the cell
somatic cell
all cells of the body excluding gamete cells
spliceosome
complex of enzymes that serves to splice out the introns of a pre-mRNA transcript
splicing
the process of modifying a pre-mRNA transcript by removing certain, typically non-coding, regions
stem cell
cell that is oligo-, multi-, or pleuripotent that has the ability to produce additional stem cells rather than becoming further specialized
telophase
final stage of mitosis (and meiosis), preceding cytokinesis, characterized by the formation of two new daughter nuclei
totipotent
embryonic cells that have the ability to differentiate into any type of cell and organ in the body
transcription
process of producing an mRNA molecule that is complementary to a particular gene of DNA
transcription factor
one of the proteins that regulate the transcription of genes
transfer RNA (tRNA)
molecules of RNA that serve to bring amino acids to a growing polypeptide strand and properly place them into the sequence
translation
process of producing a protein from the nucleotide sequence code of an mRNA transcript
triplet
consecutive sequence of three nucleotides on a DNA molecule that, when transcribed into an mRNA codon, corresponds to a particular amino acid
unipotent
describes the condition of being committed to a single specialized cell type
vesicle
membrane-bound structure that contains materials within or outside of the cell
Nội dung này đang được cập nhật.
Dưới đây là các bài văn nằm ở bên trái. Ở bên phải là các bài luyện tập (practice) để đánh giá khả năng đọc hiểu của bạn. Sẽ khó khăn trong thời gian đầu nếu vốn từ vựng của bạn còn hạn chế, đặc biệt là từ vựng Y khoa. Hãy kiên nhẫn và đọc nhiều nhất có kể, lượng kiến thức tích tụ dần sẽ giúp bạn đọc thoải mái hơn.
Despite differences in structure and function, all living cells in multicellular organisms have a surrounding cell membrane. As the outer layer of your skin separates your body from its environment, the cell membrane (also known as the plasma membrane) separates the inner contents of a cell from its exterior environment. This cell membrane provides a protective barrier around the cell and regulates which materials can pass in or out.
The cell membrane is an extremely pliable structure composed primarily of back-to-back phospholipids (a “bilayer”). Cholesterol is also present, which contributes to the fluidity of the membrane, and there are various proteins embedded within the membrane that have a variety of functions.

A single phospholipid molecule has a phosphate group on one end, called the “head,” and two side-by-side chains of fatty acids that make up the lipid tails (Figure 1). The phosphate group is negatively charged, making the head polar and hydrophilic—or “water loving.” A hydrophilic molecule (or region of a molecule) is one that is attracted to water. The phosphate heads are thus attracted to the water molecules of both the extracellular and intracellular environments. The lipid tails, on the other hand, are uncharged, or nonpolar, and are hydrophobic—or “water fearing.” A hydrophobic molecule (or region of a molecule) repels and is repelled by water. Some lipid tails consist of saturated fatty acids and some contain unsaturated fatty acids. This combination adds to the fluidity of the tails that are constantly in motion. Phospholipids are thus amphipathic molecules. An amphipathic molecule is one that contains both a hydrophilic and a hydrophobic region. In fact, soap works to remove oil and grease stains because it has amphipathic properties. The hydrophilic portion can dissolve in water while the hydrophobic portion can trap grease in micelles that then can be washed away.

The cell membrane consists of two adjacent layers of phospholipids. The lipid tails of one layer face the lipid tails of the other layer, meeting at the interface of the two layers. The phospholipid heads face outward, one layer exposed to the interior of the cell and one layer exposed to the exterior (Figure 2). Because the phosphate groups are polar and hydrophilic, they are attracted to water in the intracellular fluid. Intracellular fluid (ICF) is the fluid interior of the cell. The phosphate groups are also attracted to the extracellular fluid. Extracellular fluid (ECF) is the fluid environment outside the enclosure of the cell membrane. Interstitial fluid (IF) is the term given to extracellular fluid not contained within blood vessels. Because the lipid tails are hydrophobic, they meet in the inner region of the membrane, excluding watery intracellular and extracellular fluid from this space. The cell membrane has many proteins, as well as other lipids (such as cholesterol), that are associated with the phospholipid bilayer. An important feature of the membrane is that it remains fluid; the lipids and proteins in the cell membrane are not rigidly locked in place.
The lipid bilayer forms the basis of the cell membrane, but it is peppered throughout with various proteins. Two different types of proteins that are commonly associated with the cell membrane are the integral proteins and peripheral protein (Figure 3). As its name suggests, an integral protein is a protein that is embedded in the membrane. A channel protein is an example of an integral protein that selectively allows particular materials, such as certain ions, to pass into or out of the cell.

Another important group of integral proteins are cell recognition proteins, which serve to mark a cell’s identity so that it can be recognized by other cells. A receptor is a type of recognition protein that can selectively bind a specific molecule outside the cell, and this binding induces a chemical reaction within the cell. A ligand is the specific molecule that binds to and activates a receptor. Some integral proteins serve dual roles as both a receptor and an ion channel. One example of a receptor-ligand interaction is the receptors on nerve cells that bind neurotransmitters, such as dopamine. When a dopamine molecule binds to a dopamine receptor protein, a channel within the transmembrane protein opens to allow certain ions to flow into the cell.

Some integral membrane proteins are glycoproteins. A glycoprotein is a protein that has carbohydrate molecules attached, which extend into the extracellular matrix. The attached carbohydrate tags on glycoproteins aid in cell recognition. The carbohydrates that extend from membrane proteins and even from some membrane lipids collectively form the glycocalyx. The glycocalyx is a fuzzy-appearing coating around the cell formed from glycoproteins and other carbohydrates attached to the cell membrane. The glycocalyx can have various roles. For example, it may have molecules that allow the cell to bind to another cell, it may contain receptors for hormones, or it might have enzymes to break down nutrients. The glycocalyces found in a person’s body are products of that person’s genetic makeup. They give each of the individual’s trillions of cells the “identity” of belonging in the person’s body. This identity is the primary way that a person’s immune defense cells “know” not to attack the person’s own body cells, but it also is the reason organs donated by another person might be rejected.

Peripheral proteins are typically found on the inner or outer surface of the lipid bilayer but can also be attached to the internal or external surface of an integral protein. These proteins typically perform a specific function for the cell. Some peripheral proteins on the surface of intestinal cells, for example, act as digestive enzymes to break down nutrients to sizes that can pass through the cells and into the bloodstream.

OpenStax. (2022). Anatomy and Physiology 2e. Rice University. Retrieved June 15, 2023. ISBN-13: 978-1-711494-06-7 (Hardcover) ISBN-13: 978-1-711494-05-0 (Paperback) ISBN-13: 978-1-951693-42-8 (Digital). License: Attribution 4.0 International (CC BY 4.0). Access for free at openstax.org.

A phospholipid molecule consists of a polar phosphate “head,” which is hydrophilic and a non-polar lipid “tail,” which is hydrophobic. Unsaturated fatty acids result in kinks in the hydrophobic tails.

The phospholipid bilayer consists of two adjacent sheets of phospholipids, arranged tail to tail. The hydrophobic tails associate with one another, forming the interior of the membrane. The polar heads contact the fluid inside and outside of the cell.

The cell membrane of the cell is a phospholipid bilayer containing many different molecular components, including proteins and cholesterol, some with carbohydrate groups attached.

Nội dung này đang được cập nhật.
Dưới đây là video và các luyện tập (practice) của bài này. Nghe là một kĩ năng khó, đặc biệt là khi chúng ta chưa quen nội dung và chưa có nhạy cảm ngôn ngữ. Nhưng cứ đi thật chậm và đừng bỏ cuộc.
Xem video và cảm nhận nội dung bài. Bạn có thể thả trôi, cảm nhận dòng chảy ngôn ngữ và không nhất thiết phải hiểu toàn bộ bài. Bên dưới là script để bạn khái quát nội dụng và tra từ mới.
Script:
  1. The cell membrane provides a barrier around the cell, separating its internal components from the extracellular environment.
  2. It is composed of a phospholipid bilayer, with hydrophobic internal lipid “tails” and hydrophilic external phosphate “heads.”
  3. Various membrane proteins are scattered throughout the bilayer, both inserted within it and attached to it peripherally.
  4. The cell membrane is selectively permeable, allowing only a limited number of materials to diffuse through its lipid bilayer.
  5. All materials that cross the membrane do so using passive transport processes, which are non-energy-requiring, or active transport processes, which are energy-requiring.
  6. During passive transport, materials move by simple diffusion or by facilitated diffusion through the membrane, down their concentration gradient.
  7. Water passes through the membrane in a diffusion process called osmosis.
  8. During active transport, energy is expended to assist material movement across the membrane in a direction against their concentration gradient.
  9. Active transport may take place with the help of protein pumps or through the use of vesicles.
Bật video, nghe và điền từ vào chỗ trống.
Dưới đây là phần bàn luận. Bạn có thể tự do đặt câu hỏi, bổ sung kiến thức, và chia sẻ trải nghiệm của mình.
Subscribe
Notify of

0 Comments
Inline Feedbacks
View all comments

Ấn vào ô bên dưới để đánh dấu bạn đã hoàn thành bài học này

Hoàn Thành

Quá dữ! Tiếp tục duy trì phong độ nhé!

Đã Hoàn Thành