development and physiology

biofilm

a colony of one or some species of uni-cellular organisms that co-operate metabolically

what is dictyostelium

a cellular slime mold

dictyostelium

serves as a model for the evolution of multicellularity

motility

the movement of cells by some form of self-propulsion

the extracellular matrix (ECM)

a collection of molecules secreted by cells that provides structural and biochemical support to the surrounding cells

example of organisms that carry out spore formation

Dictyostelium, fungi

budding

simple invertebrate animals such as hydra . new individuals arise from outgrowths of existing ones

fragmentation

the body can regrow from a fragment. fragments can develop into new individuals by regeneration of lost body parts.

blastema

a heterogeneous cell mass that through migration and proliferation transiently forms at the injury site and undergoes morphogenesis to form the missing organ

parthenogenesis (virgin birth)

offspring can arise from unfertilised eggs

vegetative propagation

the vegetative part of plant can propagate without seeds

monozygotic twins

a single zygote splits in two after fertilisation. share 100% of genes

dizygotic twins

two ova fertilised separately. share about 50% of genes

diploid dominant

found in animals

alternations of generations

plants and some algae

haploid dominant

most fungi and some protists

gametogenesis

the production of gametes from haploid precursor cells

spermatogonia

differentiated primordial germ cells or the stem cells that give rise to all sperm in the embryonic testes.

what is produced in the seminiferous tubule

primary and secondary spermatocytes

whats found in the lumen

more mature cells

spermiogenesis

a differentiation - following meiosis the haploid spermatids differentiate into mature motile sperm released into the lumen.

oogenia

primordial germ cells produced by mitosis and are the stem cells of future eggs.

primary oocyte

contained within a protective follicle and are present in the ovary of the female at birth.

entire egg is divided into blastomeres

holoblastic

cell lineage analysis

mapping the origin and destiny of cells in the embryo

the acrosomal reaction

triggered when the sperm meets the egg and the acrosome releases enzymes. this triggers plasma membrane fusion and depolarization of the egg cell membrane

convergent extension

cells meet and converge causing elongation, directed by the cytoskeleton

spiral cleavage

spindle of cleavage is at an oblique angle in the cell. in mollusca and annelids

yolk sac

encloses the yolk, blood vessels develop to bring nutrients to the embryo. first site of blood production

what the ectoderm forms

epidermis of skin, nervous and sensory systems, pituitary gland, adrenal medulla, jaws and teeth

induction

\n the influence of one group of cells on a neighbouring group of cells, changing the way in which the responding cells develop

budding

carried out by simple invertebrate animals, new individuals form from outgrowths of existing ones.

allantois

disposal of metabolic waste and gas exchange

amnion membrane

surrounds the embryo, forms fluid-filled sac that bathes the embryo

the organiser experiment

demonstrated induction

organogenesis description

gastrulation brings cells into organised germ layers with location in the embryo for development of organs

neurulation

a special type of organogenesis that forms the rudiments of the nervous system

cleavage

a period of rapid cell division during early embryonic development converting a zygote to a ball of cells

gastrulation

a series of cell and tissue movements to produce a three layered embryo, the gastrula

invagination

movement of cells

coelom

a fluid-filled cavity which forms by splitting the mesoderm

what the endoderm forms

epithelial lining of digestive, respiratory, excretory and reproductive tracts

blastoderm

cap of cells on top of yolk produced by cleavage

organogenesis

the process in which organ rudiments develop from the three germ layers after gastrulation

the cortical reaction

upon fusion of the egg and sperm Ca2+

radical cleavage

seen in vertebrates and echinoderms, cleavages are equal and symmetrical

experimental embryology

physically altering the course of development by manipulating the embryo

deuterostomes

organisms with aradical cleavage pattern

arabidopsis thaliana

the model of choice for plant development

somites

mesoderm cells that form blocks on either side of the neural tube that later from different cell types

viviparity

giving birth to live young

egg activation

increased rate of protein synthesis and respiration triggered by Ca2+ ions

developmental genetics

altering genes and observing the effect on development

meroblastic

only the cytoplasm is divided and the yolk proteins are excluded

eumatazoa

animals with an organised body plan

what the mesoderm forms

skeletal and muscular systems, circulatory and lymphatic systems, notochord

acrosome

top of sperm that contains hydrolytic enzymes

chorion

outer membrane, exchanges gases between embryo and surrounding air

amniotes

animals that reproduce on dry land

polyspermy

fertilisation by multiple sperm which would lead to an increased genetic compliment and in non-viable zygote

cortical reaction

depolarisation of the membrane also leads to Ca2+ release from endoplasmic reticulum in a wave across the egg

cell differentiation

how cells become specialised

morphogenesis

how shape and structure emerge in the embryo

genome

the genetic material of an organism, the complete complement of an organisms genes

muscle cells express genes for

actin and myosin

neurons express genes for

neuroreceptors

red blood cells express genes for

globin

stem cells

are cells that are not fully differenciated

transcription

DNA sequence is used as a template for the synthesis of a complimentary mRNA

Transcription factors

regulate transcription

regulatory DNA sequences

non-coding DNA sequences that determine which cells express what gene and when they turn it on

promoters

located at the transcription start site and are needed for the assembly of transcriptional machinery

enhancers

gene-specific control regions that determine when and where a gene will be turned on

cellular differentiation in the embryo

is a result of transcriptional regulation (turning genes on and off)

crystallin

codes for the transparent molecule in the lens that allows for vision

albumin

produces a molecule that prevents liquid leaking from blood vessels

embryonic precursor cells

have the potential to become cartilage, fat cells or multinucleate muscle

determination

irreversibly commits a cell to becoming a certain cell type through molecular changes

myoblasts

cells determines to be muscle

MyoD

encodes a cell-specific transcription factor that commits the cell to becoming a skeletal muscle

MyoD cascade

a chain of events that changes non-muscle cells to muscle cells

master regulatory genes

developmental regulators

large scale mutant screens

animals are exposed to mutagens to increase the frequency of genetic damage

maternal effect genes

encode mRNA and proteins that are placed in the egg while it is maturing in then ovary

example of the maternal gene

bicoid

bicoid

needed for the formation of anterior structures in embryo

segmentation genes

divides the embryo into segments along the anterior-posterior axis

gap genes (segmentation)

subdivisions along the A/P axis

pair rule genes (segmentation)

define pairs of segments

segment polarity genes (segmentation)

define the segment and establish pattern in each segment

homeotic genes

control the anatomical identity of segments

mutations of homeotic genes

causes structures characteristic of a particular part of the animal to arise in the wrong place

cell signaling

cells influence each other’s differentiation by sending molecular signals that are converted to responses within the cell

homeobox genes

special sequence of homeotic genes that has been highly preserved

hox genes

subset of homeobox genes that are involved in positional identity, found in all organisms with an organised body plan

flash card analogy (Lewis Wolpert)

a patten could emerge in embryo cells receiving a molecular address through a set of molecular signals unique to that position

two ways cells receive information

localisation of cytoplasmic determinants, induction

grey crescent

an area of a blastula that is rich in RNA molecules

signal transduction

the mechanism that relays the signal received at the cell surface to the nucleus