Chapter 3 Flashcards
Parts of a cell?
- Plasma membrane
- Cytoplasm
- Nucleus
Plasma membrane
Separates internal environment from external environment
Cytoplasm components
- Cytosal
- Organelles
What is in the nucleus?
chromosome which contains thousands of genes
What’s the lipid bilayer made of?
(75%) Phospholipids, (20%)cholesterol, (5%)glycolipids
What are amphipathic molecules?
They have both polar and non polar parts. Hydrophilic head is polar. Hydrophobic tail is non polar.
Integral proteins
Firmly embedded in lipid bilayer, and transmembrane protein (spans entire lipid bilayer)
Peripheral proteins
Attached to polar heads or integral proteins. Many are glycoproteins they have carbohydrate groups attached to the ends that protrude into the extracellular fluid.
Glycocalyx
The portion of carbohydrate glycolipifs and glycoproteins that form an extensive sugary coat
Membranes function?
- Ion channels
- Carriers
- Receptors
- Enzymes
- Linkers
- Cell-identity markers
The lipid bilayer is highly permeable to what molecules?
Oxygen, carbon dioxide, and steroids
The lipid bilayer is moderately permeable to what?
Small, uncharged polar molecules like water and urea
What is the lipid bilayer impermeable too?
Ions and large molecules such as glucose
What do transmembrane proteins do?
Act as channels and carriers increasing the plasma membranes permeability to a variety of ions and uncharged polar molecules
What part of the plasma membrane is more positively charged and what’s negatively charged?
Inner surface is more negatively charged where as outer surface is more positively charged
Electrochemical gradient
Combined influence of the concentration gradient and the electrical gradient on movement of a particular ion
What are the two types of transport
Passive and active
Diffusion
Passive transport
Both the solutes, and solvent undergo diffusion
Factors that influence the diffusion rate?
- Steepness in concentration gradient
- Temperature - higher temp equals faster diffusion
- Mass of the diffusing substance- larger mass = slower diffusion rate
- Surface area- more surface = faster diffusion
- Diffusion distance- more distance something needs to diffuse over the longer it takes
Simple diffusion
Passive process in which substances move freely through the lipid bilayer of the plasma membranes of cells without the help of membrane transport proteins
Important in the movement of oxygen and carbon dioxide between blood and body cells, and between blood and air within the lungs during breathing
Different types of facilitated diffusion?
Channel-mediated facilitated diffusion
Carrier-mediated facilitated diffusion
Channel-mediated facilitated diffusion
A solute moves down its concentration gradient across the lipid bilayer through a membrane channel usually ion. Ions can only diffuse at particular sites. Most channels are for potassium ions and chloride ions few being for sodium ions and calcium ions
When is a channel said to be gated?
Part of the channel protein acts as a “plug” or “gate”, changing shape in one way to open the pore and in another way to close it
Carrier-mediated facilitated diffusion
A carrier moves a solute down its concentration gradient across the plasma membrane
There is a transport maximum on how much can be moved at once
Used by glucose the body’s preferred energy source
What effect does insulin have on facilitated diffusion?
Increases the transport maximum
Osmosis
Water moves through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration
What are the two ways water molecules move through plasma membrane via osmosis?
- Simple diffusion
- Aquaporins
What are aquaporins?
(AQPs) integral membrane proteins that function as water channels. They play a critical role in controlling the water content of cells
Responsible for the production of cerebrospinal fluid, aqueous humor, tears, sweat, saliva, and the concentration of urine.
Osmotic pressure
The higher the solute concentration the higher the solutions osmotic pressure
Hemolysis
Rupture of red blood cells from hypotonic solution
Crenation
Shrinkage of cells do yo hypertonic solution
What are the two sources of cellular energy that drive active transport?
- Energy obtained from hydrolysis of adenosine triphosphate (ATP)
- Energy stored in an ionic concentration gradient is the source in secondary active transport
Primary active transport
Often called pumps
Most prevalent one being the sodium potassium pump
Secondary-active transport
A carrier protein simultaneously binds to Na+ and another substance and then changes it’s shape so that both substances cross the membrane at the same time
Symporters in secondary active transport
When the transporters move two substances in the same direction
Antiporters in secondary active transport
When two substances move in opposite directions across the membrane
Endocytosis and exocytosis have what in common?
Transport vesicles
What are the three types of endocytosis?
Receptor-mediated endocytosis, phagocytosis, bulk-phase endocytosis
What are the steps in receptor-mediated endocytosis?
- Binding
2.vesicle formation - Un coating
- Fusion with endosome
- Recycling of receptors to plasma membrane
- Degradation in lysosomes
Phagocytosis
“Cell eating” Faygo sites carry out phagocytosis two main types of Faygo sites are macrophages located in many body tissues and neutrophils a type of white blood cell
Bulk-phase endocytosis
“ cell drinking” Carried out by most body cells during bulk phase endocytosis the plasma membrane folds in word and forms of vesicle containing a droplet of extracellular fluid the vesicle pinches off from the plasma membrane and enters the cytosol
What types of cells is exocytosis especially important in?
- Secretory cells that liberate digestive enzymes hormones mucus or other secretions
- nerve cells that release substances called Nero transmitters
What is transitosis?
Vesicles undergo endocytosis on one side of a cell move across the cell and then undergo exocytosis on the opposite side
What are the two components of cytoplasm?
- the cytosol
- organelles
How much of cell volume is the cytosol?
55%
What’s the location site of many chemical reactions required for cells existence?
Cytosol
What are the different types of passive transport?
1.Diffusion
2.simple diffusion
3.facilitated diffusion
4.osmosis
What are microfilaments?
The thinnest elements of the cytoskeleton
they have two general functions: help generate movement and provide mechanical support
What are the functions of the cytoskeleton?
- Serves as a scaffold that helps determine a cell shape and organize the cellular content
- Aids movement of organelles within the cell of chromosomes during cell division end of wholesales such as Phagocytes
What are the three types of protein filaments of the cytoskeleton?
1.Microfilaments
2.intermediate filaments and 3.microtubules
What are centrosomes and their function?
Centrosomes are located near the nucleus the centrosome consists of a pair of centrioles and the pericentral matrix
centrosomes can also be called the microtubule organizing centre
the pericentriole matrix of the centrism contains tubulins that build microtubules in nondividing cells the pericentral matrix of the centrosome forms the mitotic spindle during cell division
Functions of the cilia and flagella?
- Celia moves fluids along the cell surface and
- flagellum moves in entire cell
Ribosomes
Ribosomes are the site of protein synthesis
What is endoplasmic reticulum?
The endoplasmic reticulum is a network of membrane enclosed tubules that extend throughout the cytoplasm and connect to the nuclear envelope consisting of rough ER and smooth ER
Golgi complex
Consists of 3 to 20 cisterns has an entry face and an exit face socks between the entry and exit faces are called medial systems from the entry face the cisterns are thought to mature intern becoming medial and then exit cisterns
What are the steps for proteins arriving at the Golgi complex through maturation of the cisternae and exchanges that occur via transfer vesicles?
- Proteins synthesized by ribosomes on the rough ER are surrounded by a piece of the ER membrane, which eventually buds from the membrane surface to form transport vesicles
- Transport vesicles move toward the entry face of the Golgi complex
- Fusion of several transport vesicles creates the entry phase of the Golgi complex and releases proteins into its lumen
- The proteins move from the entry face into one or more medial cisterns enzymes in the medial cisterns modify the proteins to form glycol proteins, glycolipids, and Lipo proteins. Transfer vesicles that bud from the edges of the cisterns move specific enzymes back toward the entry face and move some partially modified proteins toward the exit face
- The product of the medial sister and move into the lumen of the exit face
- Within the exit face cistern, the products are further modified and are sorted and packaged
- Some of the process proteins leave the exit faith and are stored in secretory vesicles. These vesicles deliver the protein to the plasma membrane, where they are discharged by exocytosis into the extracellular fluid. For example, certain pancreatic cells release the hormone insulin in this way
- Other process proteins leave the exit phase in membrane vesicles that deliver their contents to the plasma membrane for incorporation into the membrane. In doing so, the Golgi complex adds new segments of plasma membrane as existing segments are lost in modified the number and distribution of membrane molecules
Lysosomes
Contain powerful digestive and hydrolytic enzymes that can break down a wide variety of molecules once lysosomes fused with vesicles formed during endocytosis
Autophagy
The process by which entire worn out organelles are digested
Lysosomal enzymes
Help recycle worn out cell structures and may also destroy the entire cell that contains them
Peroxisomes
Contain several oxidizes, enzymes that can oxidize ( remove hydrogen atoms from) various organic substances
Mitochondria
Referred to as the power houses of the cell mitochondrion consists of an external mitochondrial membrane and an internal mitochondrial membrane
Mitochondrial cristae
A series of folds in the internal mitochondrial membrane
What is enclosed by the internal mitochondrial membrane?
Mitochondrial matrix
Apoptosis
The orderly genetically programmed death of a cell
Nuclear envelope
Both layers of the nuclear envelope are lipid bilayer‘s similar to the plasma membrane the outer layer has many openings called nuclear pores inside the nucleus or many spherical bodies called nucleolus within the nucleus are most of the cells hereditary units genes
Nucleoli
Function in producing ribosomes.
sites of synthesis of rRNA and assembly of rRNA and proteins into ribosomal subunits
What are the bodies hereditary units?
Genes
What is the total genetic information carried in a cell or an organism?
Genome
What is the Peed like structure on a chromatin?
Nucleosome
What is the double stranded DNA wrap twice around a core of eight proteins called?
Histones
What’s the string between the beads called?
Linker DNA
What does proteome refer to?
All of an organisms proteins
What is gene expression?
When a genes DNA is used as a template for synthesis of a specific protein
What is a base triplet?
A set of three nucleotides
Codon
Each DNA base triplet is transcribed is a complementary sequence of three nucleotides
What is the genetic code?
The set of rules that relate to bass triplets sequence of DNA to the corresponding codons of irony and amino acid they specify
What are the steps in transcription?
Step one: messenger R&A directs the synthesis of a protein
step two: ribosomal RNA joins with ribosomal proteins to make ribosomes
step three: transfer RNA binds to amino acid and hold it in place on a ribosome until it is incorporated into a protein during translation
What happens in step three of transcription during the transfer RNA stage?
One end of the transfer RNA carries a specific amino acid, and the opposite end consist of a triplet of neucleotides called an anticodon. by pairing between complementary bases, the tRNA anticodon attaches to the mRNA codon
Which enzyme catalyzes transcription of DNA?
RNA polymerase
What is located at the beginning of a nucleotide sequence that states where transcription should begin?
Promoter
What term is used for where transcription ends on a DNA sequence?
Terminator
What parts of a protein will not code during transcription?
Introns located between exons
What are the steps in translation?
1.mRNA molecule binds to the small ribosome subunit at the mRNA binding site. a specialty tRNA called initiator tRNA binds to the start codon on mRNA were translation begins the tRNA anticodon attaches to the mRNA codon by pairing between the complementary bases besides being the start codon AUG is also the codon for the amino acid Methionine. Thus, Methionine is always the first amino acid in a growing polypeptide
2. The large ribosomal subunit attaches to the small ribosomal subunit mRNA complex, creating a functional ribosome. The initiator tRNA with it amino acid(methionine) fit into the P site of the ribosome
3. The anticodon of another tRNA with it attached amino acid pairs with the second mRNA codon at the ace site of the ribosome
4. A component of the large ribosomal Subunit catalyzes the formation of a peptide bond between Methionine and the amino acid carried by the tRNA at the A site
5. Following the formation of the peptide bond the resulting two peptide proteins becomes attached to the tRNA at the A site
6. After peptide formation, the ribosome shifts the mRNA strand by one codon. The tRNA in the P site enters the E site and is subsequently released from the ribosome. The tRNA in the A site bearing the two peptide protein shifts into the P site, allowing another tRNA with its aminoacid to bind to the newly exposed codon at the A site. steps three through six occur repeatedly and the protein lengthens progressively.
7. Protein synthesis ends when the ribosome reaches a stop codon at the A site which causes the completed protein to detach from the final tRNA in addition tRNA vacates the P site and the ribosome split into its large and small subunits
What does several ribosomes attached the same mRNA constitute?
Polyribosome
What is a somatic cell?
Any cell of the body other than a germ cell
What is a germ cell?
A gamete or any precursor cell destined to become a gamete
What happens in somatic cell division?
A cell undergoes a nuclear division called mitosis and a cytoplasmic division called cytokinesis
What is reproductive cell division?
The mechanism that produces gametes
What are the different phases in somatic cell division?
Interphase
G1 phase
G0 phase
S phase
G2 phase
mitotic phase
The two chromosomes that make up each pair of genes are called what
Homologous chromosomes
Because somatic cells contain two sets of chromosomes they are called what?
Diploid (2n) cells
During which phase does the cell do most of its growing?
Interphase
What is mitosis?
Mitosis is the distribution of two sets of chromosomes into two separate nuclei it is an exact partitioning of genetic information and a continuous process
What are the steps of mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
What does the centromere do
Holds the chromatid paired together
What is cytokinesis?
Division of a cells cytoplasm and organelles into two identical cells is called cytokinesis
When does cytokinesis take place?
Cytokinesis takes place in late anaphase with the formation of a cleavage furrow
What is a cleavage furrow?
A slight indentation of the plasma membrane and is completed after telophase
What is necrosis?
A pathological type of cell death that results from tissue injury
What is meiosis?
The reproductive cell division that occurs in the gonads produces gametes in which the number of chromosomes is reduced by half
How many chromosomes does a gamete contain and what are they refer to?
Gametes contain a single set of 23 chromosomes and are called haploid cells
When is meiosis complete?
After two successive stages meiosis one and meiosis two
How are cells different?
- Sizes- measured in micrometers
- Shapes- related to function
Cell cycle
An orderly sequence of events in which a somatic cell duplicated contents and divides into consists of interphase and mitotic phase
Interphase consist of what three phases?
G1
S
G2
