The Cell Flashcards
What are cells
The structural and functional units of an organism
The smallest structure capable of performing all functions necessary to life
What terms describe the amount of cells an organism has
Unicellular - one cell
Multicellular - at least 2 cells, can be many many more
What are the three types of cell in nature
Prokaryotic : lack a membrane enclosed nucleus. Simple bacteria
Eukaryotic: have a membrane bound nucleus, and organelles. Protists, fungi, plants, animals
Archaeans: posses qualities of both, archaebacteria
What are the three statements of cell theory
- all organisms are made of cells
- cells are the basic living unit for all life
- cells come from previous cells
How big are cells
Small
Less than 1 mm
Some as small as 1 um (1/1000 mm)
Why do cells need to be small
Cells consume food and produce waste, this is relative to cell volume
Cells thus need to take in food and let out waste, this is relative to cell surface area
As a cell becomes bigger the volume increases at a faster rate than surface area
At a certain size the cell would not be able to take in enough food to feed it fast enough, and let out enough waste fast enough
What might cells do to increase surface area
The outer membrane might fold and wrinkle to increase surface area without increasing volume
What are the main cells we learn about
Eukaryotic cells, they have a nucleus and organelles. And form the base of animals, plants, fungi, and protists
What is the cell membrane
A phospholipid bi-layer that is embedded with protein molecules,
Surround the cell and separates the inside of the cell from the out
What fills the inside of the cell
A semi fluid medium called cytoplasm,
Composed of water, salts, and dissolved organic molecules
What are cell walls
A permeable but protective wall that is around the cell membrane, gives rigidity and protection to certain cells
What types of cell have cell walls
Plants cells have 1 cellulose and 1 lignin cell wall
Fungi have cellulose and chitin cell walls
Some algae have cellulose cell walls
What are organelles
Well defined sub cellular structures that perform a specific, important function for the cell
What is the nucleus
A prominent organelle with a diameter of ~5um
Stores the genetic information of the cell, DNA, and controls cell functions
What is inside the nucleus
Chromatin: DNA + Proteins, condenses into chromosomes
What is the semi fluid inside the nucleus
Nucleoplasm
What is the nucleolus
The area where ribosomal RNA (rRNA) is produced
What is around the nucleus
The nuclear envelope
What is attached to the nuclear envelope
The rough ER
What are nuclear pores
Holes around 100nm that permit bidirectional transport of proteins and ribosome subunits
What do ribosomes do
Synthesis proteins using mRNA as a template
What are ribosomes made of
Small + large subunits, each is a complex of unique ribosomal RNA and proteins
Where are ribosomes found
In the cytoplasm, groups called polyribosomes, and RER
What organelles are in the endomembrane system
Nuclear envelope + ER + golgi + vesicles
Does transport and processing of the cell
What is the Endoplasmic Reticulum
Complicated system of membranous channels and sacs (flattened vesicles)
Connects to nuclear envelope
What is the rough ER
Studded with ribosomes which synthesis proteins
Inside the RER proteins are processed and modified
What is the smooth ER
Connected to rough ER, has no ribosomes
Synthesizes phospholipids, producers testosterone, detoxifies drugs, stores calcium ions
Forms vesicles which transport materials to golgi
What is the Golgi apparatus
3-20 slightly curved sacs, stacked on top of each other
One side faces nucleus, other faces membrane
What does the Golgi apparatus do
Receives proteins + lipid vesicles from ER, as they move through they are modified, repackaged into secretory vesicles
Forms lysosomes
What is secretion
Secretory vesicles move from Golgi and release materials outside cell
What are lysosomes
Membrane bound vesicles produced by Golgi
Contain hydrolytic digestive enzymes
What do lysosomes do
Digest food molecules into simpler subunits
White blood cells use them to eat bacteria
Consume food, garbage, and old organelles
What are vacuoles
Large membranous sacs, larger than vesicles
Store substances like water, sugars, salt, pigment, toxins
Bigger in plant cell
What are peroxisomes
Similar to lysosomes, membrane bound vesicles that envelope enzymes
Synthesized by cytoplasmic ribosomes and transported by carrier proteins
What enzymes are in peroxisomes
Enzymes produce H2O2 which is broken down into water + oxygen by another enzyme called catalase
Vary between cells
What do chloroplast do
Use solar energy to synthesis carbohydrates
6C02 + 6H20 -> C6H12O6 + 6O2
What do mitochondria do
Brake down carbohydrates while producing ATP
C6H12O6 + 6O2 -> 6CO2 + 6H2O + 38 ATP
What is the structure of chloroplasts
4-6 um in diameter 1-5 um long
Contains chlorophyll
2 membranes enclose fluid called stroma
Membrane system folds into flattened sacs called thylakoids in stacks called grana
What is the structure of mitochondria
0.5 - 10 um in diameter 2-5 um long
Double membrane around fluid matrix
Inner membrane folds to form cristea which give more surface area
What are the 3 parts of the cytoskeleton
Actin filaments (microfilaments)
Intermediate filaments
Microtubules
What are microfilaments
7nm wide
Long, thing, flexible fibres
Bundles + mesh like networks
2 globular actin monomers twisted around in a helical manner
Form a web, make pseudopods
What are intermediate filaments
8-11 nm wide
Rope like assembly of fibrous polypeptides that vary between tissue
Support nuclear envelope, membrane, help cell to cell interactions
What are microtubules
Small, hollow cylinders
25 nm wide, 0.2-25 um long
Made of globular protein tubules of 2 types, 23 rows of tubulin dimes around empty core
What are centrioles
2 structure found in animal cells
May be involved in microtubules assembly + disassembly
Short cylinders of microtubules that become centrosomes
What are centrosomes
Structures that manipulate chromosomes during cel division
What are cilia and flagella
Hair like projections that move cells
Undulate, whip, stiffly or like oats
Cilia are shorter
Membrane bound cylinders of 9 around 2 centre
What is the cell membranes purpose
To separate the inside of the cell from the out
To regulate entrance and exit of molecules to maintain homeostasis
What is the main part of the cell membrane
The phospholipid bilayer, a fluid like membrane that can stiffen and strengthen due to cholesterol
What are the two types of proteins in a cell membrane
Peripheral = one side
Integral proteins = span both sides may only protrude on one though
What is the fluid-mosaic model
Membrane structure of phospholipids, proteins that can move laterally through them, and steroids
What carbs are involved in the cell membrane
Glycolipids and glycoproteins
Play roles in cell identification
What do peripheral proteins do
Play a structural role and help stabilize and shape membrane
What are channel proteins
Involved in passage of molecules through membrane, have a channel, and possibly a gate
What are carrier proteins
Combine with substance to move it across the membrane
What are cell recognition proteins
Glycoproteins help recognize pathogenic invasion to start immune reaction
What are receptor proteins
Shapes allow specific proteins to bind to it, changing its shape to bring about a cellular response
What are enzymatic proteins
Carry out metabolic reactions directly
How permeable is the cell membrane
Selectively permeable, some particles can cross others cannot
What is diffusion in cells
The passage of small particles and gases through the cell membrane from high to low concentrations passively
What factors can affect diffusion
Temp, pressure, electrical currents, molecule size
What is osmosis
The diffusion of water molecules
What is osmotic pressure
Pressure that developed due to osmosis in a system
What is an isotonic solution
A solution that has an equal solute/water concentration inside and outside a membrane (cell)
What is a hypotonic solution
A solution that causes water to move into a cell, making it swell or lyse.
There is less solute concentration out of the cell
What are the terms for cell disrupted by hypotonic solutions
Cytolysis : disrupted cell
Hemolysis : disrupted red blood cell
Turgor pressure : plant cell that Is swelling but can’t lyse due to rigid cell wall
What organisms have to be adapted to withstand hypotonic solutions
Those living in fresh water
What are hypertonic solutions
Cause cell to shrivel / shrink
More solute concentration outside cell
Water moves out of cell
What two terms describe the affects of hypertonic solutions to cells
Crenation: shriveling of a cell in hypotonic solutions
Phasmolysis: membrane pulls off of cell wall due to crenation in plant cell
What types of organisms need to be adapted to hypertonic solutions
Marine animals
How are molecule transported by carrier proteins
A specific molecule / ion bonds to the protein, which then changes shape moving the material across the membrane
What is facilitated transport
Allows passage of glucose + amino acids, even though they can’t pass through lipids
Passive
Specific proteins
What is active transport
Opposite to diffusion direction (low to high[])
Needs energy:ATP
Carrier proteins can pump materials across
Sodium potassium pump moved 3 Na then 2 K ions across
What is exocytosis
A vesicle fused to membrane opening out side the cell to release materials in a process called secretion
Release hormones, neurotransmitters, digestive enzymes
What is endocytosis
A portion of the cell membrane folds around materials to bring it into the cell in a vesicle
Multiple types
What is phagocytosis
Large molecules like food particles
Often leads to lysosome digestion materials
Seen on light microscope
What is pinocytosis
Liquids or small molecules
Happens a lot though you need a e- microscope to see
What is receptor mediated endocytosis
Pinocytosis but in an area (pit) where receptor proteins bind to specific molecules
Vitamins, peptide hormones, lipoprotein, etc
Effecient, used to transfer materials between cells
