lecture 1.6: cells and chromosomes · 2019. 9. 3. · prokaryoteseukaryotesmammalian development...

Prokaryotes Eukaryotes Mammalian development

Unit 1: Theoretical Pillars of Biology

Lecture 1.6: Cells and Chromosomes

John D. Nagy

BIO 181: General Biology for Majors, Scottsdale Community College

2019 Revision

John Nagy Lec 1.6: Cells and Chromosomes 1/23


Outline

1 Prokaryotes

2 EukaryotesCharacteristicsOrganellesGenetic organization

3 Mammalian developmentPatternsProcesses



Macromolecules self-organize

Stromatolites—giant mats of photosynthetic bacteria(cyanobacteria)



Prokaryotic cell (Bacteria)

Key characteristics:

No nucleus or othermembrane-boundorganelles

One majorchromosome andmany smallchromosomes(plasmids)

Bacterialchromosomes tendto be circular



Cell walls and cell membranes

Plasma (cell) membranes:

In all cells.

Composed of phospholipids (soap) and proteins.

Thin; behave like soap bubbles.

Cell walls:

In many prokaryotes, single-celled eukaryotes, all plantsand fungi.

Composed of carbohydrates (cellulose in plants, chitin infungi) or peptidoglycans (carbohydrates and proteins).

Rigid.



Protein synthesis machinery

Cell structure: Ribosome

Ribosomes are cell structures (“organelles”) composed ofribosomal RNA (rRNA) and protein that construct proteins inall known cells. They are the fundamental cell structures.



Bacterial DNA


Prokaryotes Eukaryotes Mammalian development Characteristics Organelles Genetic organization

Eukaryotic cell

Key characteristics:

Has membrane-boundorganelles, including anucleus (stained green inpicture).

Has a cytoskeleton (stainedyellow in picture).

Most of the DNA is in thenucleus.

Nuclear chromosomes tendto be linear.



Eukaryotes also have ribosomes...



...along with a bunch of other stuff...



...and even more stuff

Study the functions of structures on this and the previous slide.



Eukaryotic DNA—Chromatin

See Cold Spring Harbor Labs, DNA Learning Center:dnalc.cshl.edu/resources/3d/08-how-dna-is-packaged-advanced.html



Condensed eukaryotic DNA



Chromosomes pack into the nucleus

A 3-D model ofchromosomalpacking in anucleus.

Based onmathematicalmodel and anaylsisof experimentaldata.

Credit: Di Stefanoet al., NationalCentre for GenomicAnalysis (Spain).



Chromosomal patterns in mammals

Spectral karyotype of a human female.



Chromosomal patterns in mammals

Human pattern similar for all mammals and many othermulticellular eukaryotic organisms:

Definition: Diploid

Cells or organisms in which a majority of cells contain twocomplete sets of chromosomes are called diploid.

Definition: Haploid

Cells or organisms in which a majority of cells contain one setof chromosomes are called haploid.

Definition: Homologous chromosome

In diploid organisms, homologous chromosomes are similarin size, shape, location of the centromere and gene content.


Prokaryotes Eukaryotes Mammalian development Patterns Processes

Early embryonic development



Embryo to fetus



Fetal development



Process 1: Cell proliferation

Definition: Mitosis

Mitosis refers to division ofthe cell nucleus.

Definition: Cytokinesis

Cytokinesis is division of thecell contents.

Cells that fail to meetcheckpoint criteria typicallycommit suicide (apoptosis)Proliferation constructsaround 1013 new cells fromthe original zygote.



Prior to mitosis, cells must replicate DNA



Process 2: Differentiation

Definition: Differentiation

Differentiation is the process by which an unspecialized cell,often a stem cell, becomes specialized. In mammals, makes≈ 200 cell types.



Process 3: Morphogenesis

Arrows point to cellsundergoing apoptosis.

Definition: Apoptosis

Apoptosis is geneticallyprogrammed cell death.


lecture 1.6: cells and chromosomes · 2019. 9. 3. · prokaryoteseukaryotesmammalian development...

Documents