BIS 2D Quiz 2 (Days 8-12)

cell division

process by which a parent cell divides into two or more daughter cells

cytokinesis

the physical process of cell division

binary fission

how prokaryotic cells divide, single circular DNA molecule replicates and division occurs by the invagination of the plasma membrane and the laying down of new cell wall between the two chromosomes to produce two separate daughter cells

why is it important to have coordinated growth of cell membrane and cell wall?

if it was not coordinated eventually would have small cells that would be too small to be functional therefore must be coordinated to generate the right amount of cell wall and plasma membrane, and to generate the copies of the chromosome

mitosis

part of cell cycles when replicated chromosomes are separated into two new nuclei to produce two genetically identical daughter cells

phases of mitosis

prophase, prometaphase, metaphase, anaphase, telophase

is interphase a part of mitosis? what happens during it?

no it is before, microtubules undergo rapid reorganization

what happens during prophase?

chromosomes condense and centrosomes move to opposite sides of the nucleus, initiating formation of the mitotic spindle

what happens during prometaphase?

mitotic spindle organization between 2 cells getting ready for division

what happens during metaphase?

chromsomes and mitotic spindles now ordered.

what happens during anaphase?

The chromosomes separate and move along spindle fibers to opposite ends of the cell

what happens during telophase?

Chromosomes uncoil, spindle microtubules break down, nuclear envelope reforms

how much time of the cell cycles does mitosis take up?

less than 10%

length of cell cycles for humans vs bacteria vs yeast

humans 12-24 hr, bacteria 30 min, yeast 2-4 hr

at which stage of the cell cycle does chromsome duplication occur? When does chromsome segreation and cell division occur?

S- phase (synthesis), M-phase (mitosis)

order of cell cycle

G1, S, G2, M

are there checkpoints during the cell cuycles to make sure everything is ocuring correctly and regulation is occuring?

yes, for example before and after S phase

what is the role of the cytoskeleton in cell division?

microtubules forms the mitotic spindle to separate chromsomes into daughter cells, the minus end is typically anchored at the center of the cell

alpha ________ and beta __________ dimers assemble into longitudinal repeating uings called _______________. 13 of them assemble into a microtubule. These filaments are ______________ meaning that each end is distinct. The minus end is anchorded at the __________ and the plus end is _________________. The assembly is _________________.

tubulin, tubulin, protofilaments, directional, centor of the cell (MTOC), grows out into the cell, reversible

why are there dynamic instability of microtubules?

due to the structural differences between a growing and shrinking microtubules plus end

mitotic or meiotic spindle

transient microtubules based structure that is present during mitosis and that mediates accurate separation of chromosomes to the daughter cells

Nucleation of MT occurs at ______________ at which the negative end of the MT is anchored by ______________ proteins

microtubule organizing center (MTOC), centrosome

_______________ radiate from centrosomes and act to provide force to pull spindle poles apart. __________ attach chromsomes at centromeres. _____________ provide structure at the spindle.

astral MT, kinetochore MT, overlap MT

what happens when two kinesines interact that are each on microtublues from opposite centrosomes?

each microtubles are growing in a different direction, so when kinesins interact they are stuck and instead the microtubules move and pushes the centrosomes apart. eventually so much force that it physically breaks apart,

microtubule based motor protein(s) + direction if applicable

dynein (negative direction) and kinesin (positive direction)

microfilament/actin based motor protein(s) + direction if applicable

myosin

role of conventional myosin

cell contractions (generates cleavage furrow during cytokinesis), migration, and cytokinesis

role of dynein and kinesin and unconventional myosin

transport of organelles, vesicles, mRNAs, chromsomes etc.

somatic cells

any cells of the organism that are not the reproductive (germ) cells

germ cells

reproductive cells

meiosis

results in four daughter cells called gametes containing half the number of chromosomes of parental cells, only done in germ cells (sexually reproducing organisms)

what happens in meiosis 1?

duplicated homologous chromsomes separate leading to one version with two copies of it present in each cell, making haploid

what happens in meiosis 2?

separation of copies of homologous chromosomes to different cells, still haploid

daugher cells meiosis vs mitosis

meiosis: haploid, not genetically identical, two rounds of cell division, 4 daughter cells; mitosis: diploid, genetically identical, 1 round of cell division, 2 daughter cells

fertilization

fusion of haploid gametes, produces diploid cell that undergoes repeated rounds of cell division to produce a new organism

seed

embryonic plant enclosed in a protective outer covering, product of ripened ovule after fertilization by poell nadn some growth within the mother plant

mammal development (4 steps)

zygote, 2 cell stage, 8 cell stage, 64 cell stage morula/blastula

the early embryo undergoes ___________ in which some cells from the ___________ migrate to ______________. this is when ___________ are formed.

gastrulation, outside, inside of the embryo, the three embryonic layers (ectoderm, mesoderm, and endoderm)

why has there been a lot of research on frog development as opposed to human development?

a lot of research done on frogs because developed externally with eggs, can even see zygote, while humans are harder because they are developed internally

potency

cells ability to differentiated into other cell types

determination

cell's decision to differentiate into a certain cell type

stem cells

an undifferentiatied cell of a multicellular organisms which is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation

at the 8 cell stage, one cell can still break off and _________________ while at the 64 cell-stage morula/blastula _________________

differentiate to make a whole organisms, cannot because more restrictive at this stage in development

totipotent

cell can create a whole organism, can make all of the different cell types in the body plus the placenta because the zygote is totipotent

pluripotent

cells can give rise to all the different cell types in the body

mulitpotent

cell can give rise to more than one type but is more limited than pluripotent

mature

cell is fully differentiated post-mitotic cell, such as muscle cell

embryonic cell migration in animal embryos create _____________________

three embryonic layers: ectoderm, mesoderm and endoderm

ectoderm is ________________. endoderm is __________________. mesoderm is____________

skin and nervous system, guts lungs glands, muslce heart bone

lineage

a group of cells that are derived from the same progenitor

lineage tracing

follow a group of cells that are derived from the same progenitor to their final state (use dye injected into cells to see where each eall goes)

what are the two mechanisms that give rise to difference cell types generated during development?

asymmetric cell division (intrinsic determinant) and inductive interactions (symmetric cell division followed by extrinsic determinant)

what is the main different in the process of embryogensis between animals and plants

animal development is largely buffered against environmental changes and the embryo generates the same genetically determined body structure unaffected by external conditions while plant development on the other hand is dramatically influenced by the environment and since they cannot match themselves to their environment by moving from place to place plants adapt instead by altering the course of development; additionally seeds can remain dormant for years after fertilization while animals this is not naturally possible (IVF makes it possible); germ cells arise later in development from somatic cells in plants while in animals germ cells arise very early in development

meristems

group of stem cells actively dividing into daughter cells that will eventually differentiate resulting in entire organs, plant embryos have two meristems that together are able to create a whole adult plant

what do you need to build an organism?

cells, tissues, organ, organ system, organism

systems, organs and tissues of plants

systems: shoot, root; organs: root, stem, leaf; tissues: dermal, vascular, ground

types of tissues in animals

connective, nervous, epithelial, mucle

muscle tissues

made of cells that can respond to signals (excitable) and contract (contractile) to generate movement

epithelial cells

made of cells which cover surfaces and create barriers or form glands specialized in secretion (neatly stacked with bumpy microvili which allows for protection and increases surface area which alows from more reactions like absorption

nervous tissues

made of cells that can create, transmit, and respond to signals to communicate information between different parts of the body

connective tissues

made of cells and extracellular material that "fill the gaps" between tissues and provide support and protection, all cells are derived from the same lineage

what is the predominant cell type in connective tissues and what does it do?

fibroblasts, secretes abundant extracellular matrix proteins

extracellular matrix (ECM)

complex network of polysaccharides and proteins secreted by cells, confers the structure that permits the tissue to withstand compressional and tensile forces and to keep cells together in the context of a tissue

how much metabolic effort does it take for fibroblasts to produce ECM proteins?

a lot because they are very large

three main components of ECM

fibrous proteins, proteoglycans, and the lamina

proteoglycans

form highly hydrated gel-like matrix because of OH group in sugar in which fibrous proteins are embedded, this gel is able to resist compressive forces while permitting rapid diffusion of nutrients, metabolites, and hormones between the blood and tissue

fibrous proteins

single polypeptide chains that are very large such as collagen which are trimeric proteins that organize into collagen fibrils that aggregate into collagen fibers and they strengthen and help organize the matrix and rubber like elastin fibers give it resilience; can also be adhesive proteins such as fibronectin(tendon, cartilage) or laminin

what is the problem with collagen-elastin cream?

not actually able to strengthen collagenbecause cannot get across epithelial layer

basal lamina

composed of many laminin and acts as a tight barrier with the epithelium, organizes underlying connective tissues, organization allows to keep and everything in place and provides the function for different tissue types

what is the ECM of plants

the cell wall (pectin (branched polysaccharides), cellulose and lignin (fibrous proteins))

how are epithelial cells organized to create an effective barrier?

proteins made by epithelial cells are embedded in the plasma membrane of the cells and proteins in adjacent cells are able to form tight interactions with each other to hold cells together. proteins in the cell membrane also have the ability to interact with laminin to form right barriers

can things fit in between epithelial cells?

no, the membrane protein interactions with other membrane proteins from a protein belt or cinch that prohibits anything from getting through unless there is a genetic mutation, infection by particular bacteria, etc.

_______________ occur at points of cell-cell and cell-matrix in all tissues, and are highly abundant in the epithelia because ______________. ________ are classified as ________________

specialized cell junctions, purpose of epithelium is to provide barrier and to cover surfaces, cell junctions, occluding anchording or communicating

what is the advantage of interaction with the cytoskeleton on the intracellular side while interactions with membrane proteins onthe outside?

act as anchor, prevents diffusion of structures being adhered, provides strong barrier and organization, extracellular binding domains are not enough to provide this stable interaction

gap junction

allows passage of small water-soluble ions and molecules and is useful to communication (signals propagated through channels), nutrients, and organization

cell adhesion molecules (CAMs)

connect cells to each other or to the ECM, all have hydrophobic patch because embedded in plasma membrane and the plasma membrane is hydrophobic so must be hydrophobic in that section also, contains binding sites for cytoskeletal elements, interacts with itself (or rather other proteins of same type), contain repeating domain motif that is really good at binding

what happens is cells were not adhesive? if were hyperadhesive?

if not adhesive would be problem because wouldnt be able to control uptake of nutrients and various other things, if hyperadhesive many not be a problem in a gut but would be if present in developent because lots of migration needs to occur and bining to different proteins so if hyperadhesive couldn't move which is bad because needs to be dynamic

cell adhesion is a _________ process. cells can alter their adhesive properities and ______________ the epithelium. The cells then ______________ and form ______________.

dynamic, disengage from, migrate away, a variety of cell types and tissues throughout the embryo

how is neutrophil migration mediated?

dynamic CAM interactions

How can cells sort themselves in terms of CAMs?

can sort themselves according to teh types and level of CAMs they express, cells with a lot of a particular CAM want to bind with cells also with a lot of that same one so that all free CAMs are bound

How to cells maintain stable and strong interactiosn with CAMS?

by having a lot, "the velcro principle", individual CAMs have low affinity for their interacting partner so a single interaction is weak, and as a consequence, transient therefore many are needed to be strong

how can CAMs be changed and whys is this important?

can be changed and regulated to decrease number of them etc. which allows cells to be dynamic

each cell has a particular combination and amount of ____________ that enables it to bind __________________. The simultaneous binding of ______________ increases __________________.

CAMs, in its own characteristic way to other cells and the ECM, CAMS to other cells and the ECM, the strength of interactions