Chapter 3 Flashcards by Alisha Lee

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

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Where does homeostasis start?

In the cells

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How many cells do humans have?

~30-40 trillion

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What does the plasma/cell membrane do?

Separates the intracellular fluids from the extracellular fluids, regulates passage of substances

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What is considered the intracellular fluids of a cell?

Cytoplasm

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What does the cell membrane regulate?

Entry and exit of ions, nutrients and such

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How does the cell membrane do this?

Through receptors able to analyze the environment and communicate to cells

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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

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What does cholestorol do for the cell membrane?

Stiffens it, makes it less permeable, and is used in regulatory functions

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What protiens are associated with the cell membrane?

Integral protiens, peripheral protiens

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Where are integral protiens?

Inside the membrane

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Where are peripheral protiens?

Bound to the inner or outer surface

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What do trans-membrane protiens do?

Allow substances to traverse across the cell membrane

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What is considered the cytoplasm?

All materials between the cell wall and the nucleus

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What is the cytosol?

Mixture of water and dissolved things, jelly-like

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What are organelles?

Internal structuresof eukaryotic cells that have specific functions

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What are inclusions?

Masses of insoluble materials in cells (glycogen granules in liver+skeletal muscle cells, liquid droplets in fat calls, pigment granules)

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What are non membraneous organelles?

Completely in contact with the cytosol/cytoskeleton

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What is the cytoskeleton?

Internal framework of protiens in the cytoplasm for strength and flexibility

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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

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What do intermediate filaments do?

Strengthen cell, maintain cell shape, stabilize positions of organelles

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What are microtubules?

Largest hollow tubes of tubulin, radiate outwards towards the centrosome. Help intermediate filaments strengthen cell, cell shape, organelles, movement

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What is a centrosome?

Region of cytoplasm near nucleus that organizes microtubules

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What are centrioles?

Cells in the centrosome cylindrical structures that form spindle apparatus for cell division

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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