Exam Three: Part Three

Question 1

what are CELLS?

Answer 1

• the BASIC BUILDING BLOCKS of life
• give STRUCTURE, NUTRIENTS, conversion of nutrients into ENERGY–carry specialized FUNCTIONS
• have DNA–can make copies of themselves
• classified into two groups;
  PROKARYOTES
  EUKARYOTES

Question 2

what is the STRUCTURE and FUNCTION of the PLASMA MEMBRANE?

Answer 2

STRUCTURE:

made up of specific PHOSPHOLIPIDS
HYDROPHOBIC TAILS + HYDROPHOBIC HEADS
- creation of a BILAYER–CELL MEMBRANE
- they help separate the INSIDE LIVING PART of the cell from the OUTSIDE ENVIRONMENT
- SEMIPERMEABLE; small molecules can move in and out (water, salt, noncharged particles etc…)

FUNCTION:
- have EMBEDDED PROTEINS within its bilayer to carry out specific FUNCTIONS
- TRANSPORT OF MOLECULES
-CELL-CELL RECOGNITION
- SENSES ENVIRONMENT

Question 3

what is the FLUID MOSAIC MODEL?

Answer 3

• the plasma membrane is a FLEXIBLE LAYER
• PHOSPHOLIPDS + PROTEINS are not STATIC–move FREELY within the MEMBRANE

FUNCTIONS:
- CELL ATTACHMENT
- moves molecules within the bilayer
- allows membranes to FUSE RAPIDLY
- allows proteins to move within membrane as needed
- ensures EVEN DISTRIBUTION evenly among daughter cells

Question 4

what affects the FLUDITY of the MEMBRANE?

Answer 4

• TEMPERATURE
  can make the membrane too rigid or too fluid/flexible
• CHOLESTEROL
  keeps BILAYER FLUID in various environmental conditions
  keeps PHOSPHOLIPIDS TOGETHER - don’t separate too far
• SATURATED/UNSATURATED FATTY ACIDS
  animal cells have more saturated fatty acids

Question 5

describe the PROTEINS within the PLASMA MEMBRANE

Answer 5

PERIPHERAL PROTEINS
- lie at the OUTER AND INNER SURFACE
- loosely asso. with the PM
- easy removal
INTEGRAL PROTEINS
- part of the PM
- only removed by DISRUPTION
known as TRANSMEMBRANE PROTEINS; if complete PENETRATION of the MEMBRANE

Question 6

what is important about the MOVEMENT OF MATERIAL across the MEMBRANE?

Answer 6

• helps provide NUTRIENTS for METABOLISM
• supplies OXYGEN for RESPIRATION
• SECRETES WASTE
• secretes ENZYMES and other PROTEINS

Question 7

what are the specific ways to move material across the membrane?

Answer 7

PASSIVE (NO ENERGY)
- simple diffusion
- facilitated diffusion
ACTIVE (ENERGY)
- cell uses energy (ATP) to move a substance across the membrane

Question 8

describe SIMPLE DIFFUSION (p)

Answer 8

the MOVEMENT of MOLECULES FROM AN AREA of HIGHER CONC. to an area of LOWER CONC.
- continues till all molecules are EVENLY DISTRIBUTED–EQUILIBRIUM

• sees SMALL MOLECULES diffuse across PM; no energy needed

Question 9

describe FACILITATED DIFFUSION (p)

Answer 9

• use of INTEGRAL MEMBRANE PROTEINS to function as CHANNELS that move MOLECULES across the PM
  - known as TRANSPORTERS; no energy needed

Question 10

describe OSMOSIS (p)

Answer 10

• the diffusion of WATER through a semi-permeable membrane from a higher concentration to a lower concentration to establish a DYNAMIC EQUILIBRIUM
• NO ENERGY
• helps flow WATER into the PM

Question 11

what are the three kinds of OSMOTIC SOLUTIONS?

Answer 11

• ISOTONIC:
  
  • no net movement of water
• HYPOTONIC:
  
  • more solutes inside the cells so water molecules move INTO the cell, making the cell BURST
• HYPERTONIC:
  
  • more solutes outside the cell, the water MOVES OUT of the cell, making the cell SHRINK

Question 12

describe ACTIVE TRANSPORT

Answer 12

• uses ENERGY to move substances across the PM
  
  • helps transport ions, amino acids, or sugars

WHY?
- allowing cells to ACCUMULATE NEEDED MATERIAL
ex. sodium and potassium pump

again sodium is already naturally entering the PM through the diffusion of nonspecific transporters

• can sacrifice some sodium to pump greater amounts of potassium into the cell!

Question 13

describe GROUP TRANSLOCATION

Answer 13

• occurs only in PROKARYTOES
• the substance coming in is CHEMICALLY ALTERED DURING TRANSPORT
  
  • once altered, the PM is impermeable - cannot leave the cell! 😮
    *use of ENERGY

Question 14

describe PROKARYOTIC CELLS

Answer 14

• NO NUCLEUS
• everything is FLOATING around the membrane
• DNA has NO surrounding membrane
• all FUNCTIONS occur in their actual CYTOPLASM

Question 15

what is a CAPSULE (GLYCOCALYX) (p)?

Answer 15

the VISCOUS GELATINOUS polymer that is secreted and is external to the cell wall of many prokaryotes

• ORGANIZED/FIRMLY ATTACHED to cell wall
  
  • considered a CAPSULE
• UNORGANIZED/LOOSELY ASSOCIATED to cell cell
  
  • considered a SLIME LAYER

Question 16

what is FLAGELLA (p)?

Answer 16

• LONG HAIR-LIKE structure that moves bacteria
• flagella rotate CLOCKWISE OR COUNTERCLOCKWISE
  the movement of flagella
  - move into getting nutrients, disease, or getting away from threats

PARTS:
- FILAMENT external to the cell
- HOOK
- BASAL BODY in the membrane
(has a MOVEMENT SENSOR–tells direction of filament to move cc or c)

Question 17

what is BACTERIAL MOTILITY?

Answer 17

• specific bacteria that can sense STIMULI in their environment like food or toxins
  
  • uses FLAGELLA to swim toward or away from stimuli

Question 18

what is TAXIS?

Answer 18

• movement of bacteria TOWARDS or AWAY from stimuli
• CHEMOTAXIS:
  
  • movement towards CHEMICALS
• PHOTOTAXIS:
  
  • movement towards LIGHT

Question 19

what are AXIAL FILAMENTS, PILI, an FIMBRAIE?

Answer 19

AXIAL FILAMENTS:
flagella that are under an outer sheath + SPIRAL around the cell

PILI:
- short and small appendages
- TWITCHING motility & GLIDING motility
- twitching movement to move 😀

FIMBRIAE:
- SHORT HAIR LIKE appendages that stick to each other and surfaces, involved in forming BIOFILMS

Question 20

what is the CELL WALL? (p)

Answer 20

SEMI-RIGID structure;; helps survive various conditions of hypotonic or hypertonic solutions

• prevents BACTERIAL CELLS FROM RUPTURING IN HYPOTONIC SOLUTIONS
• contributes to PATHOGENESIS
• the site of ANTIBIOTIC ACTION
• made up of a network of MACROMOLECULES:
  called PEPTIDOGLYCAN;
• quite UNIQUE–target of antibiotics
  PENICILLIN prevents the proper formation of the PEPTIDOGLYCAN LAYER–weakens cell wall

    has two types; Gram+ (thicker) & Gram- (thinner)

• use of GRAM STAINS for identification

Question 21

describe CYTOPLASM + STRUCTURES (4)(p)

Answer 21

CYTOSKELETON
- has DIFFERENT FIBERS within the cytoplasm
- has similar functions to a eukaryotic cytoskeleton; cell division, growth, shape, and DNA movement

NUCLEOID
- a type of BACTERIAL CHROMOSOME—long CiRCULAR thread of DNA
- area of the cell where most condensed DNA & DNA ASSO. PROTEINS are found
- length of DNA can be a THOUSANDS TIMES greater than cell
(has PLASMIDS–small CIRCULAR DNA–
helps with the transferring of
PATHOGENESIS FACTORS + TRANSFER OF
BACTERIA)

RIBOSOMES
- PROTEIN BUILDERS of cell
- made from 2 SUBUNITS with rRNA & proteins
- 50S subunit + 30S subunit

ENDOSPORES
- created with NUTRIENTS ARE DEPLETED–specific resting cells
- RESISTANT TO UV RADIATION, lack of water, HIGH TEMPS ETC…

Question 22

how do PROKARYOTIC CELLS REPRODUCE?

Answer 22

reproduce ASEXUALLY by a process called BINARY FISSION

Question 23

describe FLAGELLA and CILIA in EUKARYOTES

Answer 23

FLAGELLA
- few LONG PROJECTIONS
- flagella moves in a WAVE LIKE MANNER
CILIA
- short and many

both made up of MICROTUBULES

Question 24

describe CELL WALL (E)

Answer 24

• much more SIMPLER than the PROKARYTOIC CELL WALL

in ALGAE and PLANTS –CELLULOSE

on FUNGI–made up of POLYSACCHARIDE CHITIN
*both provide PROTECTION and SUPPORT

OTHERS and ANIMAL CELLS
- don’t have cell wall; have a PM covered with GLYCOCALYX
(layer of STICKY CARBS)
- strengthens the CELL SURFACE
- greater CELL-TO-CELL ATTACHMENT
- RECOGNITION

Question 25

describe PLASMA MEMBRANE + ENDOCYTOSIS (e)

Answer 25

- quite similar in FUNCTION AND BASIC STRUCTURE - contains STEROLS--CHOLESTEROL uses the process of ENDOCYTOSIS transports material ACROSS THE MEMBRANE BY ENGULFING IT

Question 26

describe CYTOPLASM + STRUCTURES (3) (e)

Answer 26

EUKARYOTIC CYTOSKELETON - much more COMPLEX - made up of SMALL RODS AND CYLINDERS - important for SHAPE, TRANSPORT, ORGANELLE ATTACHMENT, and MOVEMENT--cytoplasmic streaming EUKARYOTIC RIBOSOMES - known as the 80S RIBOSOME - LARGER AND DENSER than pro. RIBOSOME - found FREE and ATTACHED to ER (ER ATTACHED--synthesizes proteins that are MEMBRANE PROTEINS/EXPORTEd) (FREE--synthesizes proteins needed INSIDE the CELL) - SYNTHESIZES PROTEINS needed INSIDE THE CELL MEMBRANE BOUND ORGANELLES - nucleus - ER - etc....

Question 27

describe NUCLEUS (e)

Answer 27

-- contains ALMOST ALL hereditary material—DNA!! - seen within the nuclear membrane/envelope - nuclear pores CHARACTERISTICS: - has LINEAR DNA HISTONES- proteins that are associated with our DNA - help compact the DNA - protection for DNA against damage

Question 28

what about CHROMOSOMES?

Answer 28

the NUCLEUS has MULTIPLE CHROMOSOMES CHROMOSOMES - DNA molecules that package tightly around HISTONES into THREADLIKE STRUCTURES - can be **HAPLOID (one copy) or DIPLOID (two copies)**

Question 29

describe MITOSIS vs MEIOSIS

Answer 29

EUKARYOTES can multiply by ASEXUAL and SEXUAL REPRODUCTION (more common) ASEXUAL REPRO.; MITOSIS - similar to BINARY FISSION - have MULTIPLE CHROMOSOMES that are replicated and divided between the 2 daughter cells SEXUAL REPRO: MEIOSIS - only happens in **DIPLOID CELLS** - creates FOUR genetically distinct gametes using HOMOLOGOUS chromosomes (each has 1/2 chromosomes from the mother cell) FERTILIZATION: - gametes from both male and female fuse to form the **ZYGOTE** - **full complement** of the chromosomes - important for a greater rate of GENETIC DIVERSITY

Question 30

describe CENTROSOMES (e)

Answer 30

- an ORGANELLE near the NUCLEUS - contains the CENTRIOLES - this is where we have the SPINDLE FIBERS develop during CELL DIVISION

Question 31

describe the ER ENDOPLASMIC RETITUCULUM (E)

Answer 31

- ENDOPLASMIC RETICULUM: - an extensive network of FLATTENED MEMBRANE SACS - ROUGH ER: - continuous with NUCLEAR MEMBRANE - outer surface covered in RIBOSOMES - production and folding of and dispatch of some proteins - SMOOTH ER: - extends from the ROUGH ER + NO RIBOSOMES - helps SYNTHESIZE phospholipids, fats, and steroids (estrogens)

Question 32

describe the GOLGI COMPLEX (e)

Answer 32

- made up of 3-20 CISTERNAE - flattened membrane vesicles - very FIRST STEP in the TRANSPORT OF PROTEINS made in the rough ER to other regions of the cell - helps with MODIFYING proteins to form GLYCOPROTEINS AND LIPOPROTEINS

Question 33

describe MITOCHONDRIA + MITOCHONDRIAL DNA

Answer 33

- makes ATP—THE POWERHOUSE OF THE CELLLL!! - contains CIRCULAR DNA - contains 70S ribosome - contains machinery that aids in REPLICATION, TRANSCRIPTION, and TRANSLATION - can also grow and divide 🙂 MITOCHONDRIAL DNA: - carries 37 GENES - important for normal mitochondrial function - the mitochondrial disease is **MATERNALLY inherited**

Question 34

describe CHLOROPLASTS

Answer 34

- present within ALGAE + PLANTS - contains the pigment CHLOROPHYLL in THYLAKOIDS - has enzymes required for PHOTOSYNTHESIS - also contain 70S RIBOSOME, CIRCULAR DNA, and ENZYMES - similar to the mitochondria

Question 35

describe LYSOSOMES

Answer 35

- made from the GOLGI COMPLEX - contains around 40 DIGESTIVE ENZYMES - breaks down WASTE AND FOOD - breaks down DYSFUNCTIONING ORGANELLES - can DIGEST BACTERIA that enter the cell

Question 36

describe VACUOLES

Answer 36

- CAVITY in the cytoplasm of a cell that is enclosed by a MEMBRANE - within plants - occupies over 5%-90% of the cell FUNCTIONS: - temporary STORAGE - brings food in by ENDOXYTOSIS - stores METABOLIC WASTE AND TOXINS - takes up WATER — rigidity of water and leaves

Question 37

what is the ENDOSYMBIOTIC THEORY?

Answer 37

states that the MITOCHONDRIA and CHLOROPLAST in eukaryotic cells were once aerobic bacteria (prokaryotes) that were ingested by a larger proto-eukaryotic cell - ENDOSYMBIOSIS: - living together with one organism inside the other - EVIDENCE? - both mitochondria and chloroplast have; - own CIRCULAR DNA - 70S ribosomes - can REPLICATE their DNA