Chapter 4 Notes Flashcards
(35 cards)
1
Q
Endosymbiotic Theory
A
- Hypothesis explaining how eukaryotic cells and organelles originated (evolved) from prokaryotic cells
1. Chloroplast and mitochondria started out as small prokaryotes
2. Bigger prokaryotes engulfed these smaller prokaryotes
3. These smaller prokaryotes did not digest, therefore they lived in symbiosis with the bigger cell
4. This created eukaryotes
2
Q
Prokaryotic cell characteristics
A
- small and simple
- 0.1 to 5.0 um in size
- unicellular
- nucleus is absent
- circular DNA
- single haploid chromosome
- lack membrane-bound organelles
- reproduce both sexually and asexually
- cell division by binary fission
- examples are bacteria and archaea cells
3
Q
Prokaryote and Eukaryote characteristics
A
- have cell (plasma) membrane
- have cytoplasm
- have ribosomes
- have dna
4
Q
Eukaryotic cell characteristics
A
- large and complex
- 10 to 100 um in size
- unicellular or multicellular
- nucleus is present
- linear dna
- paired diploid chromosome
- has membrane-bound organelles
- mostly reproduced sexually
- cell division by mitosis and meiosis
- examples are plant, animal, fungi, and protists
5
Q
Cell differentiation
A
- explains how cells become specialized
- All body cells use different parts of your dna - they don’t have different dna
- Formed in blastocysts which is where stem cells are found
- blastocysts - early stage of the embryo
- stem cells - “blank slate” can become any type of Specialized cell
- cancer is a type of cell diff.
6
Q
Internal and external cues for stem cells
A
Internal:
- Signals controlled by genes in dna
- transcription factors (responsible for progression of specific cell type)
External
- Chemical secretions from tissue
- signaling from other cells
- environmental factors
7
Q
Nucleus
A
- contains most of the cell’s dna
- controls the cells activities by direction protein synthesis by making messenger RNA (mRNA)
- DNA is associated with many proteins in structures called chromosomes
8
Q
Nuclear Envelope
A
- double membrane
- pores that allow material to flow in and out of nucleus
- attached to a network of cells
9
Q
Nucleolus
A
- prominent structure in nucleus
- site of ribosomal RNA (rRNA) synthesis
10
Q
Ribosomes
A
- involved in the cell’s protein synthesis
- ribosomes are synthesized from rRNA produced in the nucleus
- cells that must synthesize large amounts of protein
- some ribosomes are free, others are bound
11
Q
Free ribosomes
A
- suspended in cytoplasm
- typically make protein that functions in the cytoplasm
12
Q
Bound ribosomes
A
- attached to the rough ER
- associated with proteins packed in certain organelles
13
Q
Endomembrane system
A
- many of the membranes within a eukaryotic cell are part of the endomembrane system
- some of these membranes are physically connected and some are related by the transfer of membrane segments by tiny vesicles (sacs made of membranes)
- many of these organelles work together in the synthesis, storage, and export of molecules
Includes:
- nuclear envelope
- ER
- golgi apparatus
- lysosomes
- vacuoles
- plasma membrane
14
Q
Smooth ER
A
- lacks attached ribosomes
- involved in a variety of diverse metabolic processes
- produces enzymes important in the synthesis of lipids, oils, phospholipids, and steroids
- other enzymes help process drugs, alcohol, and other potentially harmful substances
- some helps store calcium ions
15
Q
rough ER
A
- lines the outer surface of membranes
- Makes additional membrane for itself
- makes proteins destined for secretions
16
Q
golgi apparatus
A
- serves as molecular warehouse and finishing factory for products made by the ER
- products transport in vesicles form the ER to the golgi
- one side of golgi is a receiving dock and the other is a shipping dock
- products are modified as they go from one side to the other - sent out in vesicles
17
Q
Lysosome
A
- a membranous sac containing digestive enzymes
- the enzymes and membrane are produced by the ER and transferred to the golgi apparatus for processing
- the membrane serves to safely isolate the potent enzymes from the rest of the cell
18
Q
Lysosome - food particles
A
- help digest food particles engulfed by the cell
1. A food vacuole binds with a lysosome
2. The enzymes in the lysosome digest the food
3. the nutrients are then released into the cell
19
Q
Lysosome - damage
A
- help remove or recycle damaged parts of a cell
1. The damaged organelle is first enclosed in a membrane vesicle
2. a lysosome fuses with the vesicle; dismantles its contents; breaks down the damaged organelle
20
Q
Vacuoles
A
- large vesicles that have a variety of functions
- some protists have contractile vacuoles that help to eliminate water from the protists
- in plants vacuoles may:
- have digestive functions
- contain pigments
- contain poisons that protect the plant
21
Q
Mitochondria
A
- organelles that carry out cellular respiration in nearly all eukaryotic cells
- cellular respiration converts chemical energy in foods to chemical energy in ATP (adenosine triphosphate)
- two internal compartments (see other card)
22
Q
Mitochondria - internal compartments
A
- Intermembrane space: the narrow region between the inner and outer membranes
- mitochondrial matrix: mitochondrial dna; ribosomes; many enzymes that catalyze some of the reactions of cellular respiration
23
Q
Chloroplasts
A
- the photosynthesizing organelles of all photosynthesizing eukaryotes
- photosynthesis is the conversion of light energy from the sun to chemical energy of sugar molecules
- has compartments
24
Q
thin intermembrane space
A
found between outer and inner membrane of chloroplasts
25
Chloroplasts and mitochondria
- have dna and ribosomes
- structure of these ^ is similar to those in prokaryotic cells
- Endosymbiotic theory proposes that m and c were formerly prokaryotes and began living in larger cells
26
Inner membrane of chloroplast
- contains thick fluid called stroma that contains the DNA, ribosomes, and many enzymes
- A network of interconnected sacs called thylakoids
- in some regions, thylakoids are stacked like poker chips. Each stack is called a granum where green chlorophyll molecules trap solar energy
27
cytoskeleton
- network of protein fibers which function in structural support and motility
-3 kinds of fibers
scientists believe that motility and cellular regulation result when the cytoskeleton interacts with proteins called motor proteins
28
3 fibers in cytoskeletons
- microfilaments: (actin filaments) support the cells shape and are involved in motility
- intermediate filaments reinforce cell shape and anchor organelles
- Microtubules (made of tubulin) give the cell rigidity and act as tracks for organelle movement
29
flagella and cilia - other functions
- while some protists have -- that are important in locomotion, some cells of multicellular organisms have them for different reasons
1. cells that sweep mucus out of our lungs have cilia
2. animal sperm are flagellated
30
flagella vs cilia
- a flagellum - longer than cilia - propels a cell by an undulating, whiplike motion
- cilia work more like the oars of a crew boat
- Flagella and cilia have a common structure and mechanism of movement
- 9+2 pattern - rings of 9 microtubules surrounds a central pair of microtubules - anchored in basal body
31
flagella and cilia movement
- move by bending motor proteins called dynein feet
- these feet attach to and exert a sliding force on an adjacent doublet
- the arms then release and reattach a little further along and repeat this time after time
- this walking causes the microtubules to bend
32
decline in sperm quality
- environmental chemicals
- genetic disorders that interfere with movement of sperm and cilia
PcD - immotile sperm
33
ECM
- extracellular matrix - may attach to a cell through glycoproteins that bind to membrane proteins called integrins. Integrins span the plasma membrane and connect to microfilaments of the cytoskeleton
34
Cell junctions
- adjacent cells communicate, interact, and adhere through specialized junction between them
1. tight junctions prevent leakage of extracellular fluid across a layer of epithelial cells
2. anchoring junctions fasten cells together into sheets
3. gap junctions are channels that allow molecules to flow between cells
35
cell walls
- a plant cell, rigid cell wall protects and provides skeletal support keeping the plant upright and is primarily composed of cellulose
- plant cells have cell junctions called plasmodesmata that serve in communication between cells
