The Plant Cell And The Cell Cyle Flashcards
Prokaryote
Eukaryote
Before a nucleus - bacteria and archaea
-lack nucleus (DNA not surrounded by membrane)
-have circular bacterial chromosome in nucleoid
-lack membrane bound organelles
-non cytoskeleton
True nucleus
-DNA linear in nucleus
-membrane bound organelles
-cytoskeleton
Protoplast
Contents of cells Consisting of a cytoplasm with membrane bound organelles and a nucleus
Plasma membrane functions
- Separates protoplast from outside
- Mediates transport in and out
- Synthesis of cell wall microfibrils (cellulose)
- Detects and responds to hormonal and environmental signals
Tonoplast
Single membrane around vacuoles
Cytoplasmic streaming or cyclosis
Movement within the cell as long as cell is alive
Nucleus functions
- Controls ongoing activities by determine which and when protein molecules are produced
- Stores genetic info (DNA) - nuclear genome
Endoplasm if reticulum
A complex system of membranes that plays a central role in cellular biosynthesis.
Chromatin and chromosomes
Threads and Grains easily distinguished
During division, chromatin become condensed until visible as distinct chromosomes
Haploid
Diploid
Polyploid
Number of chromosomes in gametes is half the somatic cell
Somatic cell (double set)
3n, 4n, 5n
Nucleoli
A small spherical body found in the nucleus of eukaryotic cells; composed chiefly of rRNA that is in the process of being transcribed from copies of rRNA genes; the site of production of ribosomal subunits
Ribosomes
Small particles, consisting of protein and RNA. Has a large and small subunit produced in nucleolus and transported to cytoplasm, where they are assembled into ribosomes. Ribosomes are where amino acid are linked together to form proteins
May aggregate into polysome areas
Plastids
Concerned with photosynthesis and storage-chloroplasts (with chlorophyll and carotenoid), chromoplasts, and leucoplasts
Plastids are differentiators into a membrane system consisting of flattened sacs called thylakoids and a matrix called the stroma
Chloroplast jobs besides photosynthesis
Involves in synthesis of amino acids, fatty acids and a number of secondary metabolites and temporary storage of starch
-contain own DNA
Chromoplasts
Pigmented plastids of variable shape, lacking chlorophyll but synthesize and retain carotenoid pigments (yellow, orange, red). Has no membranes
May develop from previous chloroplasts (ripening of fruits from green to yellow)
Leucoplasts
Lack pigments and an elaborate system of inner membranes. Some synthesize starch, other are capable of forming oils and proteins.
Lest differentiated
Contains amyloplasts
Proplastids
Small, colourless, or pale green undifferentiated plastids that occur in meristematic cells of roots and shoots. Precursors to highly differentiated plastids. In embryos, pro plastids of seeds first develop into etioplasts, and then with light become chloroplasts
Can become amyloplast, chromoplasts or mature chloroplast
Prolamellar bodies
Proplastid differentiation development is arrested due to a sense of light, a prolamellar body is formed.
Etioplasts
Plastids containing prolamellar bodies
-form in lead cells of plants grown in the dark. When exposed to light, the eptioplasts develop into chloroplasts, and membranes of prolamellar bodies develop into thylakoids
Mitochondria
Like plastids, are surrounded by 2 membranes. Inner membrane has numerous invaginations called cristae to increase surface area for proteins and reactions. Generally smaller than plastids.
Sites of respiration, a process involving the release of energy from organic molecules and it’s conversion to molecules of ATP.
What organelle plays a role in programmed cell death
Mitochondria
In plant cells, genetic information is found in which organelles
Plastids, mitochondria and nucleus
Symbiosis
Close association between two or more dissimilar organisms that may be, but is not necessarily beneficial to each
Peroxisomes
Or micro bodies
Are spherical organelles that have a single membrane.
Some photorespirate and some contain glyoxysomes
Photorespiration
A process that consumes oxygen and releases carbon dioxide
Glyoxysomes
Contain the enzymes necessary for the conversion of stored fats to sucrose during germination in many seeds.
Cell sap
Water based liquid filling vacuoles
Most of the increase in the size of the cell results from the enlargement of the _____
Vacuoles
Vacuole tasks
-storage for primary metabolites (sugars)
-remove toxic secondary metabolites (nicotine)
-pigmentation deposition (reds from Anthocyannins )
-breakdown of macromolecules and recycling of cell components
-keep cells turgid with water storage
Endoplasmic reticulum and the forms
A complex, 3D membrane system that permeates the entire cytosol. Communication system within the cell and as a system for channeling materials such as proteins and lipids to different parts of the cell.
Cells that sores proteins have abundant rough ER with flattened sac or Cisternae
Cells that secrete lipids have extensive smooth ER that lack ribosomes and is largely tubular
Cortical ER function
Regulate calcium in cytosol
Where are oil bodies made
ER
Lipid synthesis most abundant in seeds and fruits
Golgi apparatus and main plant function
Refers to a collective group of Golgi bodies. Consist of 5-8 stacks of flattened, disk shaped sac or cisternae. Has a forming and maturing side (with trans-golgi network). Process and secrete glycoproteins.
In plants, Golgi bodies are involved in the synthesis and secretion of noncellulosic polysaccharides destined for incorporation with cell wall.
Movement from ER, to Golgi to cell wall
ER-transition vesicles-forming face of Golgi-shuttle vesicles-trans-Golgi network-maturing face-secretory vesicles-cell membrane-cell wall
Exocytosis
Endocytosis
The secretion of substances from cells in vesicles
The uptake of extracellular substances by infolding of the plasma membrane and pinching off a vesicle.
Where are new membranes made and how are they transported
ER, transition vesicles transport to golgi and then secretory vesicles from trans-golgi contribute to plasma membrane, or tonoplast
Cytoskeleton
3D network of protein filaments that extend throughout the cytosol and are intimately involved in many processes like cell division, growth, differentiation, and movement of organelles, and structure.
Consists of two types of protein filaments: microtubules and actin filaments and may also have intermediate filaments
Microtubules
Cylindrical structures build up from subunits if tubulin which form a helix. During development one end grows faster-fast growing end is the plus end.
Constantly changing= dynamic instability
Functions: orderly growth of cell, direction of expansion, make up spindle fibres, component of flagella and cilia
Where does microtubule assembly take place
Microtubule organizing centres
Actin filaments
Polar structures with distinct plus and minus ends, composed of actin protein.
Functions: cell wall deposition, tip growth of pollen tubes, movement of nucleus before and following cell division, organelle movement, vesicles-mediated secretion, cytoplasmic streaming!
Flagella and cilia
Hair-like structures that extend from the surface of many difference types of eukaryotic cells. Relatively thin and constant in diameter, but vary in length. Shorter ones come in larger numbers, and vice versa.
Where are flagella found in plants
Only in reproductive cells (gametes), and motile sperm
Cell wall functions and it’s parts
-constrains expansion of protoplast and prevents rupture if the plasma membrane during uptake of water. Protects from pathogens.
-determines size and shape of the cell and texture of tissue
-influences final shape of plant organ
-contains variety of enzymes important to absorption, transport and secretion of substances
-role in defence of pathogens
-receive/ process information from surface and transmits to plasma membrane
-middle lamella
-primary wall
-secondary wall
-Plasmodesmata
Principal component fi plant cells walls
Cellulose
Lignin
Component of cell walls that adds compressive strength and benign stiffness.
Cutin, suberin and waxes
Fatty substances commonly found the wall of the outer, protective tissues of the plant body. Help reduce water loss from the plant.
Cell cycle
interphase:
-G1: cell doubles in size, organelles, enzymes and other molecules increase in number
-S: DNA replicates
-G2: Structures requires for cell division assemble, chromosomes condense, check for chromosome replication abnormalities, and repair of any damage to DNA.
M phase: mitosis and cytokinesis
G0 phase
Pause in progress around the cell cycle in response to environmental factors like winter dormancy
Checkpoints
In cell cycle, progression is controlled at crucial position points, near end of G1 and end of G2. At checkpoints, cycle is either stopped, or allowed to move on.
Cell plate
Initial partition between daughter cells that appears in telophase. Gross outward to fuse with cell wall.
Parts of cell wall and function
-middle lamella: pectin rich, cements adjacent cells
-primary wall: first layer with primary pit fields, dividing and metabolizing cells.
-secondary wall: interior to primary wall, contains pits, in cells needing strength and water conducting.
-Plasmodesmata: interconnect protoplast of adjacent cells, providing a pathway for substances
Plant cell main 2 components
Protoplast
Cell wall
Parts of a nucleus
Nuclear envelope
Nucleoplasm
Chromatin
Nucleolus
Inhibitor of photosynthesis and how to overcome this
Glucose and sucrose
Plant makes them into starch instead
Nuclear envelope contains
Pores that allow for transfer of materials
Polysome
Multiple ribosomes together
Makes chains of proteins efficiently through translation
Parenchyma cells stores _____ and _____ with its vacuoles
Water
Starch
Take up big portion for the cell
Plasmodesmata
Primary pit field with Plasmodesmata
-connections between cells cytoplasm directly through the cell walls.
How do chloroplasts divide
Transverse Binary fission
Chloroplasts changing position based on light
In dim light, are on top and bottom of cells, but in bright light they move to the sides.
This helps protect from too much damaging UV rays. Move by cytoplasmic streaming.
Thylakoid
Bunch of membranes on top of each other that separate stroma of chloroplasts from inner chloroplast.
Why are Grana in chloroplasts so dense?
Contain macromolecules involved in photosynthesis such as photo systems with pigments and ATPases to make ATP.
How does cell wall transmit information to the plasma membrane
Induction using Phytoalexins
Which component of the cell is involved with the synthesis and deposition of lignin
Cell wall
Polysaccharides in the cell wall
-hemicelluloses
-pectins
-Callose
Hemicelluloses
Component of cell wall
-vary greatly among cell toes and plant taxa
-hydrogen-bonded to microfibrils
-limit extensibility of cell wall
Rigid
Pectins
Component of cell wall
-primary wall and middle lamella
-cementing
-highly hydrophilic: pliability
Flexibility
Callose
Component of cell wall
-spirally wound chains of glucose
-siege elements: deposited rapidly upon wounding
-pollen tubes
What part of the cell makes the components which make up the cell wall
Plasma membrane
Primary, secondary and middle lamella
Parts of cell wall
-made first
-made second in woody plants and is thicker
-full of pectins and is in between cells
Structure of cellulose
Micelle crystalline structure->cellulose molecule->microfibrils->many microfibrils-> secondary cell wall
The secondary wall has how many layers?
3
Where is cellulose made?
Rosette cellulose syntheses within the plasma membrane
Turns UDP-glucose molecules into cellulose microfibrils
Uridine diphosphate glucose
Desmotubule
Cytoplasmic strands that connect Protoplast of adjoining cells
Plant cells have which genomes
Nuclear
Mitochondrial
Chloroplast
G1 phase
Cell doubles in size, organelles, enzymes and other molecules increase in number
S phase
DNA replicated and associated proteins synthesized; two copies of cells genetic information now exist
M phase
The two sets of chromosomes are separated (mitosis) and the cell divides (cytokinesis)
G2 phase
Structures required for cell division begin to assemble; chromosomes begin to condense
Amyloplasts contain starch true or false
True
Grana are stakes of _____ within chloroplasts
Thylakoids
Which substance makes up more than half of all living matter and more than 90% of the weight of most plant tissue
Water
The evolution of oxygenic photosynthesis was a very important event in the evolution of life because
It allowed for the origin and diversification of organism that could use a different biochemical pathway to obtain energy through respiration
