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Chapter 21 principles of development
principles of development
48
Biology
Undergraduate 1
04/24/2012

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Cards

Term

 

 

cell proliferation

Definition

 

 

-cells divid by mitosis and cytokinesis

time location and amnt of cell dividing is regulated

Term

 

 

programmed cell death

Definition

 

 

timing, lcoation, and mont of cell death are regulated

Term

 

 

 3 types of differential expansion

Definition

 

(cell movement)

-cells move past one another w/in a block of animal cells causing drasing shape changes in the embryo

 

-certain cells break awa from a block of animal cells and migrate to a new location

 

-plant cells can divid along certain planes and expand in specific directions, causing dramatic changes in shaper

Term

 

 

Cell differentiation

Definition

 

-undifferentiated cells specialize @ specific times and places in a stepwise fashion

-cells that do not undergo differentiation = stem cells

-many plant cells are capable of de-differentiating

Term

 

 

Cell-cell interation

Definition

 

 

-embryonic cells divide, die and grow mor or differentiate in response to signals from other cells

Term

 

 

proliferate

Definition

 

 

to divide and created more cells

 

-timing and extent=tightly controlled

Term

 

 

what is responsible for cell proliferation in eukaryotes?

Definition

 

-mitosis and cytokinesis

-->cells initate mitosis via reg protein MPF

-->each stage of cycle has checkpoint

-->social controls/signals from other cells determine if cells continues to grow or not

Term

 

 

meristems

Definition

(in plants)

-tissues present in same locations in embryonic and adult plants and perform the same function

 

-give rise to stems/roots/leaves/flowers etc

 

-undifferentiated cells that keep proliferating throughout life

Term

 

 

stem cells

Definition

(animals)

 

-juveniles/adults they are found in specific locations where they proliferate to replace skin/blood/gut cells that die, repair wounds, create constant supply of diseas fighting cells in immune system

Term

 

 

Apoptosis

Definition

(programmed cell death)

-due to signals from other cells; HIGHLY regulated

 

-occurs as certain tissues and organs take shape

 

(ALS-lou gehrig's disease)

Term

 

 

Cell movement/growth 

in ANIMALS

Definition

-REGULATED cell movement = KEY

-cells move to new location in order for normal development to occur (give rise to germ cells; pigment containing cells; precursosr sor blood cells, nerve cells)

-most dramatic cell movement during early processes (post rapid cell division)

-gastrulation

 

Term

 

 

gastrulation

Definition

 

 

cells in difff parts of mass rearrange themselves into 3 layers

(give rise to gut, skin, and other parts)

Term

 

 

Cell movement/growth

in PLANTS

Definition

-Differential cell growth = KEY

-->cells do NOT need to move but do change ORIENTATION of cell divisions (controls direction of cell movement and growth)

-cells incased in stiff cell walls and do not move

-directionality of cell division and cell expansion carefully regulated

Term

 

 

differentiating

Definition

 

-the process of becoming a specialized type of cell

-progressive, step by step process

 

-meristematic/stem cells-most become committed to certain cell fater EARLY in development and later become differentiated

-->look and behave like a specific cell type

Term

 

 

de differentiating

Definition

 

 

only in PLANT cells

-can change their structure and function even after the cells have been specialized

Term

 

 

totipotent

Definition

 

 

-plant cells capable of de-differentiating

"all powerful"

 

***difference btwn animal and plant cells***

Term

 

 

Importance of cell-cell interactions

 

 

Definition

-involve sending and recieving signals

-cells change activity in response to these signals

 

-signal transduction pathways trigger the production of transcription factors

-signals change patterns of gene expression-->thus embryonic cell's structures and behavior

(fate of cell relies on signals it recieves from other cells)

Term

 

 

Are all plant cells genetically equivalent?

Definition

YES

-cell de-differentiation must require genes for all types of cells not just one

-complete new individuals can be produced from a small section of root/shoot

-all plant cells contain same genes

Term

 

 

Are all animal cells genetically equivalent?

Definition

YES

-proved through nuclear transfer

DOLLY-removed mammary gland cells; grew in culture; fused w/eggs that nuclei removed

**Identical to mammary gland**

 

-clone :genetic copy

Term

 

 

How does differential gene expression occur?

Definition

 

-eukaryotic cells control gene expression @ several different levels:


-chromatin remodeling

-chromtin modification

-transcription regulation

-alternative splicing of mRNAs

-selective destruction of mRNA's

-translational rate

-activation/deactivation of proteins after they were translated

Term

 

Transcriptional

Control

Definition

 

-responsible for differentiation

-controlled by regulatroy transcription factors (in eukaryotes)

Term

 

 

Regulatory Transcription Factors

Definition

 

-influence chromatin remodeling and bind to promoter proximal elements, enhancers, silencer, or other regulatory sites in DNA

Term

 

4 axes that determine cell fate

Definition

 

1-time (organisms current stage of development)

 

+ 3 spatial demensions (3 body axis)

1.-antierior/posterior (head/tail)

2.- ventral/dorsal (belly/back)

3.-left/right

Term

 

 

pattern formation

Definition


-used to describe the events that determine the spatial organization of an embryo

 

(what becomes antierior/posterior/dorsal/ventral/right/left via what signals are sent)

 

-is a progressive process (signals repeat and each time they specify finer and finer control over what the cell becomes)

-early signals act as MASTER REGULATORS that set up general location

 

Term

 

 

Bicoid

Definition

 

-"two tailed"

-gene's product provide prositional information

-bicoid genes codes for signal that telss cell where they are located along the anterior-posterior body axis

Term

 

in situ hybridization

 

Definition

 

 

-to find where bicoid mRNAs are located in embryos

-found mRNA highly localized at anterior end

-when mRNA are translated, the protein product forms a steep [ ] gradient

-->bicoid protein is abundent in the anterior end but declines to progressively lover [ ] in the posterior end

-bicoid protein is a regulatory transcription factor

-[ ] of bicoid tells where you are in body

Term

 

 

bicoid protein

Definition

 

-regulatory transcription factor

-binds to DNA and activates genes required for the formation of anterior structures

Term

 

 

Importance of [ ] bicoid

Definition

 

[ ] of bicoid tells where you are in the body

 

HIGH [ ] = anterior (head)

LOW [ ] = posterior (tail)

Term

 

 

Difference in master regulators btwn plants and animals

Definition

 

Bicoid = TRANSCRIPTION facto

auxin = hormone********

Term

 

 

Auxin

Definition

-hormone

-enters cells and triggers the production of transcription factors that afect differentiation

-produced in meristematic cells at tip (apex) of growing embryo and is transported towards the base (roots)

 

-HIGH [ ] = top of shoot

-Low [ ] = base of roots

Term

 

hormone

Definition

 

-signaling molecule that travels through the body and acts on distant target cells

Term

 

Morphogens

Definition

 

-molecules that provide spatial info during early embryonic development, via [ ] gradient

 

-bicoid (animals-fruit fly)

-auxin (plants)

Term

 

 

segment

Definition

 

 

-region of an animal body that contains a distinct set of structures and is repeated along its lenght

Term

 

 

3 types of segmentation genes

Definition

 

 

1- gape genes

2- pair-rule genes

3- segment polarity genes

Term

 

 

Gap Genes

Definition

 

-expressed 1st, in broad regions along the head/tail axis

-define general position of segments (what part of the body the segments are in)

 

-organize cells into groups of segments long anterior/posterior axis

Term

 

 

Pair Rule Genes

Definition

 

 

-expressed 2nd

-altering bands

-pattern and order of expression suggests that pair rule genes demarcate the edges of individual segments

 

-organize cells into individual segments

Term

 

segment polarity genes

 

Definition

 

 

-expressed last

-more restricted bands

-they delineate boundaries w/in individual segments

 

-establish anterior/posterior gradient w/in each segment

Term

 

 

Homeotic genes

Definition

 

 

-products identify each segment's structural role

-trigger the development of structures that are appropriate to each type of sement

 

ex-Hox genes

Term

 

 

Hox Genes

Definition


 -homeotic genes 

-expressed in distinctive pattern along the anterior/posterior axis in early embryos and control formation of segment specific structures

 

-occur in almost every animal; # varies though

-when altered by mutations, defects in patern formation results

**genes in HOX complexes of animals are homologous**

Term

 

 

Homeosis

Definition

 

 

-replacement of one structure by another

-occurs when cells get incorrect infor about where they are in the body

Term

 

Effector genes

Definition

 

 

change proliferation, death, movement and differentiation of cells

Term

 

Master Regulator

Definition

 

-establsihes anterior/posterior gradient of embryo

 

-trigger the production of other regulatory signals and transcription factors, which trigger production of another set of signals and regulatory proteins and so on

Term

 

 

process from undifferentiated to differentiated cell

Definition

Undifferentiated

-master regulator

-gap genes

-pair-rule genes

-segment polarity genes

-homeotic genes

-effector genes

Differentiated

Term

 

 

MADS box genes

Definition

 

-in PLANTS

-analogous to homeotic genes of animals

Term

 

 

How are regulatory transcription factors and cell-cell signals active in many ways/

Definition

-reg proteins and signals are CONSERVED & REUESD

-multicellular organisms --> have common signals, signal-transduction pathways, and regulatory proteins that are used OVER & OVER during development

 

-can create diff structures b/c each deployed @ diff TIMES and LOCATION

Term

 

 

foundation of evolutionary change

Definition

 

 

-genetic changes altering developmental process in reg singals and cascade

Term

 

 

Evo-devo

Definition

 

-evolutionary development

-focuses on understanding how changes in deveopmentally impt genes lead to evolution of new phenotypes

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