Chapter 3 Flashcards
What is the 4 main points of cell theory?
Cells are the smallest living units in the human body, cells are the building blocks of all organisms, all cells come from the division of preexisting cells, cells are the smallest units that carry out meaningful life function
Where does homeostasis start?
In the cells
How many cells do humans have?
~30-40 trillion
What does the plasma/cell membrane do?
Separates the intracellular fluids from the extracellular fluids, regulates passage of substances
What is considered the intracellular fluids of a cell?
Cytoplasm
What does the cell membrane regulate?
Entry and exit of ions, nutrients and such
How does the cell membrane do this?
Through receptors able to analyze the environment and communicate to cells
How is the phospholipid bilayer structured and why?
Hydrophilic heads face towards inside and outside to attract water, hydrophobic tails inbetween to repel ions and water-solublue compounds
What does cholestorol do for the cell membrane?
Stiffens it, makes it less permeable, and is used in regulatory functions
What protiens are associated with the cell membrane?
Integral protiens, peripheral protiens
Where are integral protiens?
Inside the membrane
Where are peripheral protiens?
Bound to the inner or outer surface
What do trans-membrane protiens do?
Allow substances to traverse across the cell membrane
What is considered the cytoplasm?
All materials between the cell wall and the nucleus
What is the cytosol?
Mixture of water and dissolved things, jelly-like
What are organelles?
Internal structuresof eukaryotic cells that have specific functions
What are inclusions?
Masses of insoluble materials in cells (glycogen granules in liver+skeletal muscle cells, liquid droplets in fat calls, pigment granules)
What are non membraneous organelles?
Completely in contact with the cytosol/cytoskeleton
What is the cytoskeleton?
Internal framework of protiens in the cytoplasm for strength and flexibility
What are microfilaments?
Smallest, made of actin (motor protien), provide strength and allow attachment to membrane. Determines consistency of cytosol, interacts with myosin to produce muscle contractions
What do intermediate filaments do?
Strengthen cell, maintain cell shape, stabilize positions of organelles
What are microtubules?
Largest hollow tubes of tubulin, radiate outwards towards the centrosome. Help intermediate filaments strengthen cell, cell shape, organelles, movement
What is a centrosome?
Region of cytoplasm near nucleus that organizes microtubules
What are centrioles?
Cells in the centrosome cylindrical structures that form spindle apparatus for cell division
What are ribosomes?
Organelles that synthesize protiens
Where are free ribosomes?
Scattered throughout cytoplasm, protiens go into cytosol
Where are fixed ribosomes?
Attached to rough endoplasmic reticulum (RER), protiens go into it
What is the endoplasmic reticulum?
Interconnected cell network that sythesizes protiens, carbs, lipids, transports and detoxifies
What does the SER do?
Synthesize phospholipids and cholestorol, steroid hormones, triglycerides
What does the RER do?
Synthesis of protiens by ribosomes, fold protiens
What is the Golgi Apparatus?
Modify and package secretions, makes lysosomes for use in the cytoplasm
What are lysosomes?
Digesters and shields cell from chemical reactions that are toxic
What is autolysis?
Self-destruction of damaged cells
What is the mitochondria?
The powerhouse of the cell, numbers vary between cell types
What is the nucleus?
Control which protiens are made and when and how many, determines cell structure and function
What is the nuclear envolope?
Double membrane
What do nuclear pores do?
Let things go through so nucleus knows what’s happening in the cytoplasm.
What is the NPC?
Nuclear pore complex
What is the nucleolus?
Organelle that synthesized rRNA, assembles ribosomal subunits
What are nucleosomes?
Composed of DNA coiled around histone
What does a histone do?
Binds DNA, determines how loose it is
What is chromatin?
Non-dividing cells
What is supercoiled DNA?
Dividing cells
What is a gene?
DNA nucleotide sequence that codes for the animo acid of one protien
What is the Central Dogma of Molecular Biology?
DNA -> mRNA -> protien
What is transcription?
Synthesis of RNA from DNA, takes place in nucleus
What does mRNA do?
mRNA copies from DNA that can’t leave cell
What is a codon?
A codon is three nucleotides long
What is the transcription of this? ATATGCCGA
UAUACGGCU, DNA -> RNA
What does the transcription for DNA?
RNA polymerase
What happens to mRNA after transcription?
RNA proccesing and splicing
What is an intron?
Noncoding sequences that are removed during RNA proccessing and splicing
What are exons?
Coding segments spilced and cleaved off of introns
Where does mRNA go after proccessing and splicing?
Leaves nucleus and goes to ribosome
What compliments codons?
Anticodons
What is diffusion?
High concentration moves to lower concentration, always passive
What is the concentration gradient?
The difference between the high and low concentrations of the cell
What is simple diffusion?
Fatty acids, steroids, etc go through the interior because they’re small enough
What does channel-mediated diffusion do?
Allows small water-soluble compositions to pass through
What is osmosis?
Net diffusion of water across semipermiable membrane, ONLY water moves based on solute concentration
What is tonicity?
How a cell responds in shape to solute concentration
What is the ideal tonicity?
Isotonic
What is isotonic?
Intracellular fluid and soluce concentration is equal
What is hypotonic?
Solute of intracellular fluid is higher, water enters and the cell swells
What is hypertonic?
Solute of intracellular fluid is lower, water leaves the cell, it shrivels
What is carrier-mediated transport?
Moves molecules across membrane
What is a symporter?
2 substances go to the same direction at the same time
What is an antiporter?
2 substances go in a different direction at the same time
What is facilitated diffusion?
Large water-soluble molecules diffuse from cell membrane, bind to carrier protiens
Where do molecules bind to carrier protiens?
Receptor sites
What is active transport?
To move substances against the concentration gradient, requires energy
What are ion pumps and exchange pumps examples of?
Antiporters
What is cell division?
One cell divides into two, always happening
Why do cells need replacing?
Environment, physical wear and tear, toxins
What is apoptosis?
Programmed cell death
What are somatic cells also called?
Body cells
What goes through meiosis?
Gametes
What is interphase?
Period between cell divisions (G1, S, G2)
Can interphase vary?
Yes, skeletal cells and neurons stay in interphase forever, while stem cells never go into interphase
What does G1 phase do?
Duplication of organelles
What does S phase do?
DNA replication
What does G2 phase do?
Protien synthesis
What is a genome?
Total cell DNA
What is the M phase?
Mitosis and cytokinesis
What is mitosis?
Nuclear division
What is cytokinesis?
Cytoplasmic division
What are the stages of mitosis?
Prophase, metaphase, anaphase, telophase, cytokinesis
What happens in prophase?
Nuclear envelope disintegrates, spindle fibers contain pairs of centrioles
What is a chromatid?
Copy of chromosomes, connects to centromere
What is the point of attachment for spindle fibers?
Kinetochore
What happens in metaphase?
Sister chromatids line up in the middle of the cell at the ‘metaphase plate’
What happens in anaphase?
Sister chromatids pull apart from the shortening of spindle fibers; centromere splitting
What happens in telophase?
Nuclear membranes reform, nuclei enlarge, chromosomes unravel to chromatin, mitotic spindle breaks down
Why does the mitotic spindle break down?
It takes a lot of energy to keep it formed
What happens in cytokinesis?
The cytoplasm divides into the daughter cells
What is a cleavage furrow?
Where a contractive band of microfilaments (actin) finishes the separation of the two daughter cells
