Animal Development/Developmental Genetics - Bio 111

Chapters 51 & 20

What is development?

Formation of organs, systems, and body complexity

How is growth different from development?

Growth = more/ larger cells, development= defined traits

What is morphology?

The structure or form of an organism

Whatis a body plan?

The 3D organization of an organism

What are the three body axes?

Dorosoventral, antreposterior , lef-right

What is the dorsoventral body axis?

The line that runs from the back dorsal side) to the belly (ventral side) of an organism

What is the anteroposterior body axis?

Is the line that runs from the head anterior side) to the tail or rear end posterior side) of an organism

What is the leftright body axis?

Is the line that separates the left side of the body from the right

What cells provide cells with positional information?

Morphogens and cell adhesion molecules

What is positional information?

Signals that tell cells where to be and what to do

What is apoptosis?

Programmed cell death

What is an example of apoptosis in humans?

Removal of webbing between fingers and toes

Why do ducks have webbed feet?

Different apoptosis pattern

Why is symmetry important in animals?

Makes movement more efficient

How do plant bodies differ from animals?

They are less strict, adapted for upright growth

What are morphogens?

Chemicals in gradients that give positional information

How do cells read morphogen gradients?

Based on concentration levels

What axes domorphogers help establish?

Head-tail, back-belly

What sets early morphogen gradients?

Maternal factors in eggs

What sets later morphogen gradients?

Secretion/transport in embryo

What is induction?

Cells influence neighbors by sending signals

Do animals have cell walls?

No

What are cam's(celladnesion molecules)

Protiens that stick cells to each other and ECM(Extracellular Matrix)

Why is cell adhesion important

It positions cells and guides migration

What is cell differentiation?

Cells become specialized in shape and function

What do transcription factors do?

Control whether genes turn on or off

What are embryonic stem cells?

Undifferentiated early-stage cells

What is a source of embyonio stem cells?

Cord blood

Do adults still have skin cells?

Yes for tissue repair

What are totipotent cells?

They conform all tissue of an embeyo

What are pluripotent cells?

Can form all body cells not extra embryonic

What are multipotent cells?

Cannform some related cell types

What are the five main events of development

Fertilization, cleavage gastulation, neurlation, organogenesis

What does triplastic mean?

Embryos have three germ layers

What happens after organogenesis in some animals

Metamorphosis into an adult

In fertilization what is the acrosome reaction?

A sperm enzyme dissolves egg jelly coat

In fertilization what is the cortical reaction?

Calcium release blocks polyspermy.

What are fraternal twins?

Two eggs fertilized by two egg sperm

What ore identicaltwins?

One egg splits’, grows and has the same DNA

What is cleavage?

Cell division without growth

What is the blastula?

Hollow ball of cells after cleavage

What is the blastocysts (mammals)?

Hollow ball with inner cell mass

What is meroblastic cleavage?

Incomplete division (fish, birds)

What is holoblastic cleavage?

Complete division amphibians, mammals)

What is the animal pole?

The side with little yolk, lots of cytoplasm

What is the vegetal pole?

Side with lots of yolk

What happens in gastrulation?

Blastula becomes gastrula,

What happens when blastula becomes gastrula

3 germ layers form

What does the ectoderm form

Skin and nervous system

What does mesoderm form?

Muscles, bones, heart kidneys, blood

What does endoderm form?

Gut lining, pancreas,lungs, bladder

When do body axes first appear?

During gasturlation

What forms during neurulation?

Central nervous system

What is the neural tube?

Tube that becomes brain + spinal cord

What defect comes from failed tube closure?

Spina bifida

Steps of neural tube formation?

Plate thickness, folds, closes, epidermis seals

Wnat happenes during plate thickness of nuerulation?

The plate cells become more taller and more column-shaped, which makes the plate thicker

What happens during the folding of neurulation?

The edges of the neural plate rise up to form neural folds, while the center bends down, starting to create the neural groove

What happens during the closing of neurlation?

The neural folds fuse together to form the neural tube

What happens during epidmeis seals of neurlation?

the surface (ectoderm) cells grow over and cover the neural tube, sealing it beneath the skin layer

Where do neural crest cells come from?

Dorsal side of neural tube

What do neural crest cells form?

Skeleton, cartilage, pigment, adrenal medulla

What are somites?

Mesoderm blocks forming ribs, vertebrae, muscles

What can changes in somites cause?

Different neck/tail lengths

What is organogenesis?

Formation of functional organs

How many tissues must organs have?

At least 2, usually all 4

Example of early organ?

Heart

Example of later organ?

Lungs

What are Hox genes?

Genes controlling body plan and development.

Do all animals have Hox genes?

Yes

What does more Hox genes mean?

More body complex plan

What can Hox mutations cause?

Structures in wrong places (e.g., legs instead of antennae)