Eukaryotic Cell Cycle + 3 Domains of Life Flashcards
(64 cards)
1
Q
What is eukaryotic cell division and why is it necessary for multicellular eukaryotes?
A
- 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
2
Q
What is continuing life based on?
A
The continuity of life is based
on the reproduction of cells, or
cell division
3
Q
What is the cell cycle?
A
Cell cycle, or cell-division cycle, is a
series of events that take place in a
eukaryotic cell leading to its
reproduction.
4
Q
What is mitosis?
A
- Most cell division (via
Mitosis) results in two
daughter cells with identical
genetic information, DNA
5
Q
What is meiosis?
A
- Meiosis yields nonidentical
daughter cells that have half
as many chromosomes as
the parent cell
6
Q
The phases of the cell cycle
A
- interphase
G1 (gap1 phase)
S (DNA synthesis phase)
G2 (gap2 phase) - mitotic (M) phase
prophase
metaphase
anaphase
telophase
7
Q
What are the phases of interphase?
A
G1 Phase - Cell growth
S phase - chromosome and centrosome duplicate
G2 phase - Check DNA, Replicate organelles
8
Q
What are the events of mitosis?
A
1) Prophase
2) Metaphase
3) Anaphase
4) Telophase
9
Q
What is prophase?
A
- condensation of chromosomes;
-centrosomes assemble
10
Q
What is metaphase?
A
- spindle formation;
- nuclear membrane breakdown.
- Alignment of chromosomes on spindle equator;
- nuclear membrane disappear
- attachment of microtubules to kinetochores
11
Q
What is anaphase?
A
- Separation of chromosomes/chromatids:
- separase cleave cohesin
12
Q
What is telophase?
A
- chromosome de-condense;
- new nuclear membrane form;
- formation of two new cells
13
Q
What is the mitotic spindle?
A
- 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
14
Q
What do the centromeres do during interphase?
A
- The centrosome replicates during interphase,
forming two centrosomes that migrate to
opposite ends of the cell during prophase and
prometaphase
15
Q
What is a Kinetochore (KT)?
A
- parts of the
centromere - formed of
different proteins - microtubules
(MT) attached to
a kinetochore
16
Q
What is Cytokinesis
A
- Cytokinesis is the process of cytoplasm separation
17
Q
Checkpoints in the cell cycle
A
- The clock has specific checkpoints where the
cell cycle stops until a go-ahead signal is
received
18
Q
How are the events of the cell cycle directed?
A
- The sequential events of the cell cycle are
directed by a distinct cell cycle control system,
which is similar to a clock
19
Q
How is the cell cycle control system regulated?
A
- The cell cycle control system is regulated by
both internal and external signals
20
Q
What is the G1 Checkpoint?
A
DNA Damage checkpoint: entrance into S is blocked if genome is damaged.
21
Q
What is the S phase checkpoint?
A
DNA Damage checkpoint: DNA replication halted if genome is damaged
22
Q
What is the G2 checkpoint?
A
Entrance into M blocked if DNA replication is not completed.
23
Q
What happens when anaphase is blocked
A
Anaphase blocked if chromatids are not properly assembled on mitotic spindle
24
Q
Which scientist came up with ‘start gene’
‘check-point’ ?
A
L. Hartwell
25
Which scientist came up with CDK
P. Nurse
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Which scientist came up with cyclins
T. Hunt
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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
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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
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When is dysregulation of the cell cycle common?
* Dysregulation of the cell cycle is common during
tumorigenesis (cancer display uncontrolled growth)
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What is biological diversity or biodiversity?
* Biological diversity, or biodiversity, refers to all of the
variety of life that exists on Earth.
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What is the science of classifying organisms called?
* The science of classifying organisms is called
taxonomy.
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Why is classification important?
Classification is an important step in
understanding the present diversity and past
evolutionary history of life on Earth.
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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
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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
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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
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What is gene flow?
▪ Gene flow between populations holds a
species together genetically
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What does species mean in latin?
▪ Species is a Latin word meaning “kind” or
“appearance”
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What is phylogeny
* Phylogeny is the evolutionary history of a species or group of related species
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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
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What does sister taxa mean?
* Sister taxa are groups that share an immediate common ancestor that is not shared by any other group
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How is an organisms evolutionary history measured or determined?
An organism’s evolutionary history is
documented in its genome
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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
43
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
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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
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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
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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
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What do most bacteria cell walls contain?
▪ Most bacterial cell walls contain peptidoglycan, a network of sugar
polymers cross-linked by polypeptides
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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
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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
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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
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How do protists reproduce?
* Some protists reproduce asexually, while others reproduce sexually,
or by the sexual processes of meiosis and fertilization
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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
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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
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Number of Genes in free living bacteria and archaea
* Free-living bacteria and archaea
have 1,500 to 7,500 genes
55
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
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There are four main types of animal tissues:
▪ Epithelial
▪ Connective
▪ Muscle
▪ Nervous
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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
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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)
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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
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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
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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
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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
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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.
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