biology 02

Pro

before

Eu

true

Prokaryotic cell

• relatively small

• lacks membrane-bound organelles

• genetic material located in the nuclear area of the cytosol

Eukaryotic cell

• much more complex structurally and functionally

Plasma membrane

both prokaryotic and eukaryotic cells are bounded by this of similar construction, serving as a selectively permeable barrier

Cell wall

• may surround the plasma membrane and provide protection

• present in both prokaryotes and some eukaryotes like plant cells

Cytoplasm

• eukaryotes have membrane-bound organelles and complex cytoskeletal proteins

• both have ribosomes

Cytoskeleton

• found in eukaryotic cells

• involved in maintaining cell shape and facilitating

Ribosome

• present in both cell types, but differ in size

• involved in protein synthesis

Nucleus

• present only in eukaryotic cells

• membrane-bound organelle that contains genetic material

Simple fission

method by which prokaryotes divide

Mitosis

process used by eukaryotes for cellular reproduction

Prokaryotic flagella

• a thin protein filament that rotates to propel the cell through its environment

• simple, rotating motion

Eukaryotic flagella

• more complex and generate movement through a different mechanism

• complex, wave-like motion

Prokaryotic chromosome

• a single circular DNA molecule

• no meiosis or gamete formation occurs

Conjugation

a process in which a piece of DNA is passed from one prokaryotic cell to another

Foreign DNA uptake

Flagellum

thin protein filament that protrudes from the cell and rotates

Domain Bacteria and Archaea

2 types of prokaryotic cells

Domain Eukarya

type of eukaryotic cell

Domain Bacteria, Archaea, Eukarya

3 domains of life BAE

Archaea

evolutionarily related prokaryotes that live in inhospitable environments

Extremophiles

Archaea is often reffered to as

Methanogens

convert carbon dioxide and hydrogen gas into methane

Halophiles

• live in extremely salty environments like the Dead Sea or deep-sea brine pools

• 5M MgCl₂

Acidophiles

acid-loving prokaryotes that thrive at very low pH levels (as low as 0)

Thermophiles

live at very high temperatures

Hyperthermophiles

live in hydrothermal vents at temperatures up to 121˚C

121 celsius

the temperature used to sterilize surgical instruments in an autoclave

Bacteria

• are present in every conceivable habitat on Earth

• even found in rock layers kilometers beneath the Earth’s surface

Cyanobacteria

• photosynthetic bacteria with internal membranes that perform photosynthesis

• gave rise to green plants and an oxygen-rich atmosphere

Nitrogen fixation

is the process where certain organisms convert nitrogen gas (N₂) from the air into ammonia (NH₃) or other compounds that plants can use for growth

Metagenome

• the total genetic material (all the DNA) collected from all the microbes in a specific environment

• generating a collective genome

Microbiome

the total community of microorganisms (bacteria, fungi, viruses, etc.) living in or on a specific environment

6,000 species

prokaryote species that scientists have studied and identified.

Protists

single-celled eukaryote with specialized machinery for sensing, food capture, movement, and defense, all within one cell

Zebrafish

is a model organism for study of the stages of regeneration at the molecular level

Danio rerio

Zebra fish

Regeneration

occurs because cells that had stopped growing and dividing are suddenly stimulated to grow and divide in a highly regulated way

Cell cycle

is a repeated pattern of growth and division that occurs in eukaryotic cells.

Mitosis

a growth process that divides the replicated dna equally and precisely, generating daughter cells that are exact genetic copies of the parent cell

Meiosis

a process of sexual reproduction that produces daughter nuclei with half the number of chromosomes of the parental nucleus, with genes arranged differently from the parent cell

Sister chromatids

two identical copies of a duplicated chromosome held together by cohesins until separated in mitosis

Cohesins

hold the sister chromatids together until they are removed

Chromosome segregation

the equal distribution of chromosomes into each of two daughter nuclei

Ploidy

the number of chromosome sets in a cell or species

Haploid

• n

• one copy of each chromosome type in the nucleus

Diploid

• 2n

• two copies of each chromosome type in the nucleus, one from each parent

Polypoid

three or more complete sets of chromosomes in a cell

Homologous chromosomes

chromosome pairs in diploid cells with the same genes in the same order, one from each parent

Interphase

the phase between cell divisions where the cell grows, replicates dna, and prepares for mitosis

G1 phase

cell growth phase that can vary in length; cells may enter g0 phase here

G0 phase

resting phase where cells stop dividing; some reenter the cycle, others remain indefinitely

S phase

dna replication and duplication of chromosomal proteins

G2 phase

cell growth continues and the cell prepares for mitosis

Prophase

chromosomes condense, nucleolus disappears, and mitotic spindle begins to form from centrosomes moving to opposite poles

Prometaphase

nuclear envelope breaks down; spindle microtubules attach to kinetochores on sister chromatids

Metaphase

chromosomes align at the metaphase plate; condensation gives each chromosome a characteristic shape

Anaphase

sister chromatids separate and move to opposite poles, completing chromosome segregation

Telophase

spindle disassembles, chromosomes decondense, nucleolus reappears, and new nuclear envelopes form around each set of chromosomes

Cytokinesis

division of cytoplasm to produce two daughter cells; occurs by furrowing in animal cells or cell plate formation in plant cells

Kinetochore

is a protein structure assembled at the centromere

Centromere

is a specific region of DNA on a chromosome

Kinetochore microtubules

bind to the kinetochores

Nonkinetochore microtubules

overlap those from the opposite spindle pole

Furrow

girdles the cell and deepens until it cuts the cytoplasm into two parts

Checkpoint

a control point in the cell cycle that ensures a phase is completed correctly before the next begins

G1/S

decides whether the cell will divide; arrests if dna is damaged, nutrients are lacking, or growth factors are absent

G2/M

commits the cell to mitosis; arrests if dna replication is incomplete or damaged

Mitotic spindle checkpoint

occurs before metaphase; ensures chromosomes are attached properly to the spindle for correct alignment

Cyclins

regulatory proteins whose concentrations change as the cell cycle progresses

Cyclin-dependent kinase

• cdks

• enzymes that regulate cell cycle progression by phosphorylating target proteins; active only when bound to cyclin

Cancer

uncontrolled cell division producing a tumor; often involves loss of adhesion and the ability to metastasize

Tumor

rapidly growing mass

Metastasis

spread of cancer cells from the original site to other parts of the body, forming new tumors

Oncogenes

mutated genes that promote uncontrolled cell division or metastasis; often altered versions of genes regulating the cell cycle