developmental genetics

developmental genetics

• the field that studies the relationships between gene regulation and cell differentiation during development.

• involves a process of regulated growth that results from interaction of the genome with the cytoplasm and environment.

phenotypic trait

an expression of a genotype

new adult organism

When an organism undergoes development, a fertilized egg, or some other cell or cells derived from a parent organism is changed into a

cytoplasm and environment

Development involves a process of regulated growth that results from interaction of the genome with the

phenoclones

During development, all cells have identical genotypes, but regulatory events lead to the production of many different phenotypes or _____. They inherit a stable regulatory differentiation state, as well as a genotype, at mitosis

embryogenesis

Immediately after fertilization, the single-celled zygote will undergo

determination

where a cell makes an irreversible commitment to follow a specific developmental path; due to the cytoplasmic effector substances or determinants that cause the cell to be ireversibly commited to perform a specialized function

differentiation

the expression of cell's specialized role; unspecialized cell (such as a stem cell) becomes a specialized cell that has a specific function in the body

maternal genome

The initial cytoplasmic environment in the embryo is set by the

cytoplasmic determinants

could trigger the switching of genes.

differential gene action.

The gene products would occupy a specific position in the embryo, so when it divides, the cytoplasmic environment in each cell will be different and would trigger

DIfferential gene function

allows cells to specialize and respond to their environment. this drives the step-by-step progression of a cell from a general state to a specialized one

regulation of gene function

is the core mechanism behind how cells differentiate; also causes the physical changes seen as an embryo develops into a fully formed organism

gene expression

 the fundamental process by which the information stored in DNA is converted into functional products—primarily proteins—that carry out nearly all cellular functions. It’s a tightly regulated, multi-step journey, ensuring that each gene is expressed at the right time, place, and level

gene amplification

Differential replication of certain genes or ___ may result in larger amounts of gene products of genes which have been amplified.;  increased gene production.

DNA methylation

- typically occurs on cytosine bases in cg doublets, converting cytosine into 5-methylcytosine; addition of a methyl group to the DNA molecule, typically to the cytosine base of the DNA.

Gall (1968)

observed gene amplification in amphibian oocytes, where hundreds of copies of the nucleolar organizer region DNA were produced

euchromatin

decondensed, Active chromatin is called

heterochromatin

condensed inactive form of chromatin is called

inactive

If chromatin is highly condensed, it is

active

while if it is decondensed, it is

methylated

Pre-transcriptional control also happens if the DNA in the chromatin is highly ____ or not.

Highly methylated DNA

_ is inactive while less methylated DNA is active.

DNA transcription

may be selectively regulated within the nucleus through altering the relative rates of synthesis or by differential degradation of RNA.

immature oocyte

TRNA is synthesized rapidly by the ____ but not by

the unfertilized eggs; makes lots of rna

meiosis

No TRA synthesis is detectable during ____ and very littie,

if any, immediately after fertilization

gastrulation

The synthesis of RNA is readily observed again only at

pre-transcriptional control

refers to regulatory mechanisms that operate before

transcription begins. one way this occurs is through gene

amplification

TRANSCRIPTIONAL CONTROL

once the dna is open, the gene can be copied

into mrna (messenger rna). this is called

transcription

activator proteins

- (regulatory proteins that

boost gene transcription).

 enhancer regions -

(DNA sequences that increase

transcription, even from a distance).

 transcription factors -

(proteins that help turn

genes on or off)

RNA polymerase II

- (the enzyme that makes mRNA)

 promoter

- (a DNA sequence near the gene that

signals where transcription starts)

gene

- (a DNA segment with instructions for making

a protein)

mRNA

carries the code to make proteins)

 Gene activity speed –

Some genes copy RNA faster than

others.

Transcription factors

– Proteins that turn genes ON

or OFF

translational control

the regulation of protein synthesis at the translation stage;  to ensure proper development and cellular function. Determines whether an mRNA is translated into a protein and at what rate.

 POST - TRANSLATIONAL MODIFICATION

- a process that changes a protein after it has been made by the ribosome.COVALENT MODIFICATIONS AFTER PROTEIN SYNTHESIS ALTER PROTEIN BEHAVIOR, ACTIVITY, LOCATION, AND INTERACTION RAPID AND REVERSIBLE IN MANY CASES

PHOSPHORYLATION
UBIQUITINATION
GLYCOSYLATION N-LINKED

GLYCOSYLATION O-LINKED

ACETYLATION & METHYLATION

TYPES OF POST-TRANSLATIONAL

MODIFICATIONS

Nucleocytoplasmic interactions

refer to the dynamic communication and exchange of materials between the nucleus and the cytoplasm of a eukaryotic cell.

EPIGINETIC

MODIFICATION

reversible and heritable change in gene expression in the absence of a change in the DNA sequence in the nucleus; this modification includes chromatin remodeling, DNA methylation, and histone modification

Conrad Waddington

a British embryologist. He coined the term "epigenetics" in 1942

Blastomeres

 cell that is produced as a result of cell division or cleavage of the zygote

cytoplasm

Eggs are not homogeneous cells because of the __;  a

heterogeneous mixture of substances organized into many specific structures

Reciprocal Reaction

active genes generate new cytoplasmic environments, which

react with the genome of the cell to bring about the selective activation or inhibition of new groups of genes.

nuclear pore complexes

are the only channels through which small polar molecules, ions, and macromolecules (proteins and RNAs) are able to travel between the nucleus and the cytoplasm

Amoeba proteus

In his experiment, Goldenstein demonstrated the shuttling of

information-rich protein molecules back and forth between the

nucleus and cytoplasm of .

germinal vesicles

release into the cytoplasm some factor(s) responsible for initiating the synthesis

of DNA even in nuclei that would normally never synthesize DNA. This factor may be DNA polymerase.

Implanted nuclei

relatively small compared with blastomere nuclei, but they

swell rapidly in the mature oocyte.

 inducing tissue

can send signals to another group (the responding or induced tissue), influencing what that tissue will become

Sd Gene Mutation in mice

whenever there is a kidney, a complete ureter extends to it and whenever a ureter fails to reach the kidney region, the corresponding kidney fails to develop.

mesonephros

ureter starts as a bud from the ____ and acts as an organizer in the formation of kidney

sd sd mice

develop kidneys and ureter

Sd Sd mice

have no tails, rectum or anus, urethra, or genital papilla.

usually lack kidneys and several

vertebrae of the lower spinal column

Sd sd mice

develop complete ureter-kidney structures but have shortened

or absent tails.

smaller anterior pituitary gland and absence of

large cells that secrete growth hormone

Pituitary Dwarfism in Mice

through a comparative study, a normal and dwarf mice are compared. at first, both grew equally fast, but the dwarf mice suddenly stopped and never reached sexual maturity.

cause:

Creeper

heterozygous for a single

gene pair, in which the Creeper gene, Cp, is dominant to its normal allele. It is also found

that the homozygous Cp Cp is lethal.

Development -

refers to all the changes an organism undergoes as it grows and matures, starting from a single cell to a fully formed individual

Regulated growth

- Certain genes are turned on or off at the right time to guide the organism’s growth in a specific way.

stable regulatory differentiation state

- a consistent pattern of gene expression that

defines a cell’s identity

regulatory events

- biological processes that control gene expression, protein function, or cellular activity

methyl CpG binding domain protein

binds to methylated dna to attract other protein to modify histone structure

histone deacetylases

condense structure from euchromatin to heterochromatin

CpG island

hotspot for methylation

ROBERT

BROWN

Discovered nucleus in plant cells

1831

nucleoplasmic interactions

bidirectional flow of molecules, signals, and information between the nucleus and cytoplasm

a. Gene regulation

state of chromatin directly affects which genes are active

b. Structural Organization

organized into loops and domains that help bring

enhancers, promoters, and other regulatory elements into

close proximity

snRNAs

are integral to the formation of spliceosomes-the complexes responsible for removing introns from pre-mRNAs

a. Transcription Regulation

transcription factors binds to specific DNA

sequences to either activate or repress gene

transcription

b. Enzymatic Modifications

other enzymes modify nuclear proteins (e.g. phosphorylation, ubiquitination) to regulate their activity, stability, or interactions

a. Spatial Organization

helps organize chromatin into loops and domains

that helps for optimal function

Chromatin Remodeling and Gene Regulation

for the cell to turn on a gene, it first has to

loosen and rearrange its wrapping

RNA-Protein Complexes

not all RNA molecules simply carry messages from DNA to the parts of the cell that builds proteins. Some join forces with proteins, forming complexes that have extra duties-like editing messages or helping to set up other structures.

Dynamic assembly of nuclear bodies

specialized areas often called nuclear bodies where certain jobs are done, like making ribosomes or processing RNA