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AP Biology 2022 - 2023 > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

Light Microscopes

A

Principles: a type of microscope that magnifies images by passing light through the specimen and then the glass lenses
Advantages: can magnify an image 1,000 times the actual size - can enhance contrast - inexpensive - can observe living cells - can observe through staining (which kills the cells)
Disadvantages: cannot observe most organelles because they are too small - smallest resolution is 200 nanometers

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2
Q

Scanning Electron Microscopes

A

Principles: Microscopes that shoot an electron beam onto the surface of a specimen
Advantages: provides 3D images of cells - is able to observe very small organelles
Disadvantages: kills cells - expensive and not portable

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3
Q

Transmission Electron Microscopes

A

Principles: Microscopes that shoot a beam of electrons through the specimen
Advantages: is able to study the internal ultrastructure of cells - gives more of a diagram/drawing looking image
Disadvantages: kills the cell - expensive and not portable - has to use staining

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4
Q

Cell Fractionation

A
  • the process of taking apart cells and separating the major organelles and structures for observation
  • enables scientists to determine and study organelle function
  • achieved by homogenizing the cells first (blending them together) and then spinning the cells at varied speeds (centrifugation)
  • the higher the speed, longer the time, and the more Gs applied, the smaller the organelles that will be separated
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5
Q

Prokaryotic Cells

A
  • have no membrane bound organelles
  • no nucleus but does have a nucleoid where DNA resides
  • sometimes uses proteins in place of membranes
  • the Archaea and Bacteria kingdoms are prokaryotic
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6
Q

Eukaroytic Cells

A
  • have a nucleus with a double membrane (so four layers of membrane) called the nuclear envelope
  • does have membrane bound organelles
  • the Animal, Plant, Fungi, and Protists kingdoms are eukaryotic
  • generally larger than prokaryotic cells
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7
Q

The 4 similarities between Prokaryotes and Eukaryotes

A

1) genetic material (DNA)
2) ribosomes
3) cytoplasm
4) cell membrane

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8
Q

Why are cells small?

A
  • because maximizing surface area takes priority over the volume
  • smaller = more surface area (compared to volume) (so increases surface area to volume ratio)
  • if too small than organelles cannot function properly, or cannot fit
  • if a cell is too big, the volume increases and the surface area cannot keep up with its expansion which makes it hard for materials to enter and waste to leave fast enough without killing the cell
  • “the logistics of carrying out cellular metabolism sets limits on the size of cells”
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9
Q

Compartmentalization

A
  • the term used to describe how organelles are membrane bound; allows them to be separated with a specific job and function so that they can work together to keep the cell alive and effective
  • allows different and incompatible process to happen at the same time
  • in eukaryotes only
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10
Q

Plasma membrane (simplified)

A
  • selectively permeable membrane that surrounds the cell
  • allows sufficient passage of oxygen, nutrients, and waste to service the volume of the cell
  • a bilayer of phospholipids
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11
Q

Nuclear envelope

A
  • encloses nucleus and separates it from cytoplasm
  • double membrane, so four layers - inner membrane and outer membrane
  • contains pores made of ribosomes that can open and close to regulate the transfer of molecules between nucleus and cytoplasm
  • continuous with the endoplasmic reticulum
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12
Q

Nucleus

A
  • holds DNA in eukaryotic cells
  • ribosomes take info from DNA to make ribosomes
  • nucleolus in the center; here, rRNA combines with proteins to form the subunits of protein synthesis ribosmes
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13
Q

Explain protein synthesis

A
  • ribosomes take information from the DNA in the nucleus and follow the instructions to carry out protein synthesis
  • it happens in the cytosol (free ribosomes) and on the surface of the nuclear envelope or the rough endoplasmic reticulum (ER) (bound ribosomes)
  • rRNA combines with proteins to form the subunits of the ribosome in the nucleolus
  • DNA is transcribed into a single mRNA strand, then tRNA translates the mRNA to build chains of amino acids that grow to form proteins, this is done inside a ribosome which is rRNA
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14
Q

Ribosomes

A

Structure: Larger subunit on top and smaller subunit on bottom
- made of RNA and protein
- makes protein; the cell’s proteins synthesis site
- reads messenger RNA (mRNA) sequence and translates that genetic code into a specified string of amino acids, which grow into long chains to form proteins

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15
Q

What are the components of the endomembrane system and how are they connected?

A

Components: Nuclear envelope, Endoplasmic reticulum, Golgi apparatus, Lysosomes, Vacuoles, Plasma membrane
- connected by being continuous with each other (aka being directly connected) or via transfer by vesicles

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16
Q

Endoplasmic reticulum

A
  • accounts for more than half of total membrane in eukaryotes
  • smooth ER: has no ribosomes, has a tubular structure (like a factory plant), synthesizes lipids, metabolizes carbohydrates, stores calcium, detoxifies poison
  • rough ER: has ribosomes along surface, has a folded structure (like a maze), produces proteins and membranes that are distributed by transport vesicles, membrane factory for the cell
  • network of sacs and tubes
  • circles nucleus
17
Q

Golgi apparatus

A
  • consists of flattened membranous sacs called cisternae
  • functions: modifies products of the ER, manufactures certain macromolecules, sorts and packages materials into transport vesicles
  • cis face is the receiving side of the golgi, where substances enter
  • trans face is shipping side of the golgi, where they exit in vesicles
  • vesicles carrying materials form from and merge with golgi
  • vesicles transport specific proteins backward to newer golgi cisternae (trans face)
18
Q

Lysosomes

A
  • digestive organelles
  • where macromolecules are hydrolyzed
  • uses enzymes to recycle excess, worn out, or broken organelles/cell parts and macromolecules, a process called autophagy
  • can hydrolyze (by enzymes) proteins, fats, polysaccharides, and nucleic acids
  • can degrade material from inside and outside the cell
19
Q

Vacuoles

A
  • larger version of vesicles
  • plant and fungal cells can have many
  • membrane bound sacs with varied functions
20
Q

Name the 3 types of vacuoles and their functions

A

1) food vacuoles, formed by phagocytosis, digestive function
2) contractile vacuoles, pumps excess water out, mostly in freshwater protists
3) central vacuoles, holds water and organic compounds, key in plant growth
- can also act as storage, breakdown waste products, and conduct hydrolysis of macromolecules

21
Q

Mitochondria

A
  • place of cellular respiration
  • changes energy from one form to another
  • smooth outer
  • folded inner membrane (crinkled), called cristae
  • cristae is folded for more surface area for enzymes to synthesize atp
  • two parts in inner membrane: intermembrane space and mitochondrial matrix
  • they are semiautonomous (aka they have their own DNA) because they need information to make proteins for their job
22
Q

Chloroplasts

A
  • contain chlorophyll, makes them green
  • where photosynthesis takes place (uses enzymes and other molecules)
  • not all plant cells have chloroplasts
  • have thylakoids, membranous sacs; a stack of them are called granum; absorb sunlight
  • have stroma, the internal fluid; provide support; contain chloroplast DNA, starch, ribosomes and enzymes needed for Calvin cycle
  • they are semiautonomous (aka they have their own DNA) because they need information to make proteins for their job
23
Q

Peroxisomes

A
  • specialize in oxidation
  • surrounded by single membrane
  • contain the enzyme catalase to convert hydrogen peroxide to water
24
Q

Amyloplasts

A
  • a colorless plant plastid that forms and stores starch
  • even in plants not capable of photosynthesis
25
Q

Chromoplast

A
  • a colored plastid other than a chloroplast, typically containing a yellow or orange pigment
26
Q

Cytoskeleton

A
  • a network of fibers that organizes structures and activities in the cell
  • made of 3 molecular structures: Microtubules, Microfilaments, and Intermediate filaments
    Roles: anchoring organelles, holding cell’s shape,
  • interacts with motor proteins to produce motility
  • vesicles use it to transport materials (they are the trains and the cytoskeleton is the monorail)
27
Q

Microtubules

A
  • the thickest of the cytoskeleton components
  • hollow
    functions: cell motility (cilia or flagella), holding cell shape, regulating organelle movements, separating chromosomes during cell division
    monomer: tubulin
28
Q

Microfilaments

A
  • also called actin filaments
  • two intertwined strands of actin, solid rods
    functions: maintains cell shape and changes to it, cytoplasmic streaming (helps distribute materials faster), cell division, cell motility, muscle contraction, meant to bear tension to resist pulling forces in cell
  • the thinnest
  • microfilaments specializing in motility also have myosin protein
  • are in pseudopodia: cellular “feet” extensions that extend and contract through the microfilaments
  • grow from centrioles
    monomer: actin
29
Q

Intermediate filaments

A
  • fiberous proteins twined into a cable
  • most permanent of the cytoskeleton components
    functions: anchors nucleus and other organelles, holds cell shape, formation of nuclear lamina
    monomer: keratin
30
Q

Cilia

A
  • help to move a cell, look like hairs
  • made of microtubules
  • formed by nine pairs of microtubules + two central microtubules
  • microtubules are large and flexible to allow the cilia to move
31
Q

Flagella

A
  • found usually on prokaryotes
  • spins, creating forward movement by a corkscrew shaped filament
  • looks like a tail
  • a cell can have more than one
  • also made of microtubules
32
Q

Centrosomes

A
  • produces microtubules
  • involved in cell division
33
Q

Centrioles

A
  • the microtubule organizing center
  • in animal cells
  • has a pair of centrioles, each with either triplets or nine pairs of microtubules arranged in a ring
34
Q

What do cilia and flagella have in common?

A
  • a core of microtubules sheathed by the plasma membrane
  • a basal body that anchors the cilium or flagellum
  • a motor protein called dynein, which drives the bending movements of a cilium or flagellum
    note: both differ in beating patterns though
35
Q

Dynein and motility

A
  • dynein arms attach to one microtubule and stay fixed in place, then they grab onto the other tubule and pull it up which causes the cilia or flagella to bend (making them move), the tubule than shifts back into place for the arms to grab it again
  • protein cross-links limit sliding
36
Q

Extracellular structures

A

Includes: cell walls of plants, extracellular matrix (ECM) of animal cells, and intercellular junctions
- makes connections between cells
- helps coordinate cellular activities

37
Q

Cell wall

A
  • only in plant cells
    functions: protects the plant cell, maintains its shape, and prevents excessive uptake of water
  • made of cellulose fibers embedded in other polysaccharides and protein
  • has channels (holes) between adjacent cells called Plasmodesmata; allows for cytoplasm and material transfer (water, solutes, sometimes proteins or RNA) and keeps chemical balance of both cells equal
  • has three layers: Primary cell wall - relatively thin and flexible, Middle lamella - thin layer between primary walls of adjacent cells, and Secondary cell wall (in some cells) - added between the plasma membrane and the primary cell wall
38
Q

Extracellular matrix (ECM)

A
  • fabric like structure that covers animal cells (not a cell wall)
  • made of glycoproteins and other molecules
    functions: support, adhesion, movement, regulation
39
Q

Intercellular junctions

A
  • facilitate communications and interactions by neighboring cells through physical contact
  • tight junctions: where membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid
  • anchoring junctions: called desmosomes, fasten cells together into strong sheets
  • communicating junctions: called gap junctions, provide cytoplasmic channels between adjacent cells

AP Biology 2022 - 2023 (10 decks)

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