Eukaryotic Cell Cycle + 3 Domains of Life Flashcards
What is eukaryotic cell division and why is it necessary for multicellular eukaryotes?
- In unicellular organisms, division of one
cell reproduces the entire organism - Multicellular eukaryotes depend on cell
division for
– development from a fertilized egg
– growth
– repair
What is continuing life based on?
The continuity of life is based
on the reproduction of cells, or
cell division
What is the cell cycle?
Cell cycle, or cell-division cycle, is a
series of events that take place in a
eukaryotic cell leading to its
reproduction.
What is mitosis?
- Most cell division (via
Mitosis) results in two
daughter cells with identical
genetic information, DNA
What is meiosis?
- Meiosis yields nonidentical
daughter cells that have half
as many chromosomes as
the parent cell
The phases of the cell cycle
- interphase
G1 (gap1 phase)
S (DNA synthesis phase)
G2 (gap2 phase) - mitotic (M) phase
prophase
metaphase
anaphase
telophase
What are the phases of interphase?
G1 Phase - Cell growth
S phase - chromosome and centrosome duplicate
G2 phase - Check DNA, Replicate organelles
What are the events of mitosis?
1) Prophase
2) Metaphase
3) Anaphase
4) Telophase
What is prophase?
- condensation of chromosomes;
-centrosomes assemble
What is metaphase?
- spindle formation;
- nuclear membrane breakdown.
- Alignment of chromosomes on spindle equator;
- nuclear membrane disappear
- attachment of microtubules to kinetochores
What is anaphase?
- Separation of chromosomes/chromatids:
- separase cleave cohesin
What is telophase?
- chromosome de-condense;
- new nuclear membrane form;
- formation of two new cells
What is the mitotic spindle?
- The mitotic spindle is a structure made of
microtubules that controls chromosome
movement during mitosis - In animal cells, assembly of spindle microtubules
begins in the centrosome, the microtubule organizing centre
What do the centromeres do during interphase?
- The centrosome replicates during interphase,
forming two centrosomes that migrate to
opposite ends of the cell during prophase and
prometaphase
What is a Kinetochore (KT)?
- parts of the
centromere - formed of
different proteins - microtubules
(MT) attached to
a kinetochore
What is Cytokinesis
- Cytokinesis is the process of cytoplasm separation
Checkpoints in the cell cycle
- The clock has specific checkpoints where the
cell cycle stops until a go-ahead signal is
received
How are the events of the cell cycle directed?
- The sequential events of the cell cycle are
directed by a distinct cell cycle control system,
which is similar to a clock
How is the cell cycle control system regulated?
- The cell cycle control system is regulated by
both internal and external signals
What is the G1 Checkpoint?
DNA Damage checkpoint: entrance into S is blocked if genome is damaged.
What is the S phase checkpoint?
DNA Damage checkpoint: DNA replication halted if genome is damaged
What is the G2 checkpoint?
Entrance into M blocked if DNA replication is not completed.
What happens when anaphase is blocked
Anaphase blocked if chromatids are not properly assembled on mitotic spindle
Which scientist came up with ‘start gene’
‘check-point’ ?
L. Hartwell
Which scientist came up with CDK
P. Nurse
Which scientist came up with cyclins
T. Hunt
Cell cycle and cancer
- Increased levels of CDK molecules and cyclins are
sometimes found in human tumours, such breast
cancer and brain tumours - CDKs are potential targets for new anticancer
therapy
What has inhibition of certain CDKs been shown to do?
- Inhibition of certain CDKs has been shown to inhibit
tumour cell growth, induce apoptosis and cause
tumour regressions in animal models
When is dysregulation of the cell cycle common?
- Dysregulation of the cell cycle is common during
tumorigenesis (cancer display uncontrolled growth)
What is biological diversity or biodiversity?
- Biological diversity, or biodiversity, refers to all of the
variety of life that exists on Earth.
What is the science of classifying organisms called?
- The science of classifying organisms is called
taxonomy.
Why is classification important?
Classification is an important step in
understanding the present diversity and past
evolutionary history of life on Earth.
Example of classification
- Linnaean Classification
- All modern classification systems have their roots in
the Linnaean classification system. It was developed
by Swedish botanist Carolus Linnaeus in the 1700s. - It consists of a hierarchy of groupings, called taxa
Unity in the diversity of life
A striking unity underlies the diversity of life; for example,
* Cell is the basic structural and functional unit of all
organisms
* DNA is the universal genetic language common to all
organisms
o near university of the genetic code provides evidence of the
common ancestry of all life
* Unity is evident in many features of cell structure
What is The Biological Species Concept?
▪ The biological species is a group of
populations whose members have the
potential to interbreed in nature and produce
viable, fertile offspring; they do not breed
successfully with members of other such
groups
What is gene flow?
▪ Gene flow between populations holds a
species together genetically
What does species mean in latin?
▪ Species is a Latin word meaning “kind” or
“appearance”
What is phylogeny
- Phylogeny is the evolutionary history of a species or group of related species
What is a phylogenetic tree
- A phylogenetic tree represents a hypothesis about evolutionary
relationships - Each branch point represents the divergence of two evolutionary
lineages from a common ancestor
What does sister taxa mean?
- Sister taxa are groups that share an immediate common ancestor that is not shared by any other group
How is an organisms evolutionary history measured or determined?
An organism’s evolutionary history is
documented in its genome
How can we trace an organisms evolutionary history?
▪ Comparing nucleic acids (DNA/RNA) or other molecules to infer relatedness
is a valuable approach for tracing organisms’ evolutionary history
How is DNA that codes for rRNA useful?
▪ DNA that codes for rRNA changes relatively slowly and is useful for
investigating branching points that diverged hundreds of millions of years ago
▪ Examination of the sequences of the ribosomal ribonucleic acid (rRNA) (the
16s RNA) from different organisms and other characteristics concluded they comprised three phylogenetic domains
The Three Domains of Life
- All organisms are composed of cells.
- Differences in the structures of cells and their molecules allow all
organisms to be divided into three domains, named Bacteria,
Archaea, and Eukarya - The prokaryotes include the domains Bacteria and Archaea
History of prokaryotes?
- Prokaryotes were the first organisms to inhabit the Earth
- Prokaryotes thrive almost everywhere, including places too
acidic, salty, cold, or hot for most other organisms
What are prokaryotes?
▪ Most are unicellular, although some species form colonies
▪ Most prokaryotic cells are 0.5–5 µm, much smaller than the 10–100 µm of many
eukaryotic cells
▪ Prokaryotic cells have a variety of shapes
▪ The three most common shapes are spheres (cocci), rods (bacilli), and spirals
What do most bacteria cell walls contain?
▪ Most bacterial cell walls contain peptidoglycan, a network of sugar
polymers cross-linked by polypeptides
What is Archaea
- Archaea share certain traits with bacteria and other traits with eukaryotes
- Archaea contain polysaccharides and proteins but lack peptidoglycan
- Some archaea live in extreme environments and are called extremophiles
o Extreme halophiles live in highly saline environments
o Extreme thermophiles thrive in very hot environments
What is Domain Eukarya
- includes the protists and three kingdoms
o Plants, which produce their own food by photosynthesis
o Fungi, which absorb nutrients
o Animals, which ingest their food
What are protists
- Exhibit more structural and functional diversity than any other group
of eukaryotes - These are mostly single-celled organisms
- Some protists are less closely related to other protists than they are
to plants, animals, or fungi
How do protists reproduce?
- Some protists reproduce asexually, while others reproduce sexually,
or by the sexual processes of meiosis and fertilization
Size of the genome of bacteria and archaea
- Genomes of most bacteria and archaea range from 1 to 6 million base
pairs (Mb) - Genomes of archaea are mostly within this size range
- Eukaryotic genomes tend to be larger
Size of the genome of plants and animals?
- Most plants and animals have genomes greater than 100 Mb; humans
have 3,000 Mb - Within each domain there is no systematic relationship between
genome size and phenotype
Number of Genes in free living bacteria and archaea
- Free-living bacteria and archaea
have 1,500 to 7,500 genes
Number of genes in unicellular fungi and multicellular eukaryotes
- Unicellular fungi have about
5,000 genes and multicellular
eukaryotes up to at least 40,000
genes - Number of genes is not
correlated to genome size
There are four main types of animal tissues:
▪ Epithelial
▪ Connective
▪ Muscle
▪ Nervous
Hierarchical Organization of Body Plans
▪ Most animals are composed of cells
organized into tissues that have
different functions
▪ Tissues make up organs, which
together make up organ systems
▪ Some organs, such as the pancreas,
belong to more than one organ system
What is Epithelial tissue
▪ It covers the outside of the body
and lines the organs and cavities
within the body
▪ It contains cells that are closely
joined
▪ The shape of epithelial cells may
be cuboidal, columnar, or
squamous
▪ The arrangement of epithelial
cells may be simple (single cell
layer), stratified (multiple tiers
of cells), or pseudostratified (a
single layer of cells of varying
length)
What is connective tissue
▪ Connective tissue mainly binds and supports other tissues
▪ There are three types of connective tissue fibre, all made of protein:
o Collagenous fibres provide strength and flexibility
o Reticular fibres join connective tissue to adjacent tissues
o Elastic fibres stretch and snap back to their original length
▪ Connective tissue contains cells, including
o Fibroblasts, which secrete the protein of extracellular fibers
o Macrophages, which are involved in the immune system
In vertebrates, the fibers and foundation combine to form six major types of
connective tissue:
o Loose connective tissue binds epithelia to underlying tissues and holds organs in
place
o Fibrous connective tissue is found in tendons, which attach muscles to bones, and
ligaments, which connect bones at joints
o Bone is mineralized and forms the skeleton
o Adipose tissue stores fat for insulation and fuel
o Blood is composed of blood cells and cell fragments in blood plasma
o Cartilage is a strong and flexible support material
What is Muscle Tissue
▪ Muscle tissue is responsible for nearly all types of body movement
▪ Muscle cells consist of filaments of the proteins actin and myosin,
which together enable muscles to contract
Types of muscle tissue
▪ Muscle tissue in the vertebrate body is divided into three types:
o Skeletal muscle, or striated muscle, is responsible for voluntary
movement
o Smooth muscle is responsible for involuntary body activities
o Cardiac muscle is responsible for contraction of the heart
What is Nervous Tissue
▪ Nervous tissue is the groups of organized cells in the nervous system
▪ Nervous tissue is grouped into two main categories:
o Neurons, or nerves, transmit electrical impulses
o Glia, or neuroglia, form myelin, support and protect neurons.
