Unit 2 Flashcards
Zygote
Fertilized egg
What happens when the sperm goes inside the egg?
the zygote (fertilized egg) goes through cell division repeatedly.
Cell division through mitosis gives rise to what?
Many identical cells
Differentiation
a process that creates special structures and functions
Specialized cells become
tissues -> organs -> organ systems
stem cells
undifferentiated cells that become differentiated into one or more types of specialized cells
Embryonic Stem Cells
cells that haven never differentiated
Adult stem cells
cells found in adult bone marrow that are partially differentiated and can become bone, blood, cartilage, fat, and connective tissue
implanted blastocyst becomes gastrula:
embryo with three differentiated germ levels
Organogenesis
the process of body organ and organ system formation that follows gastrulation (folding of the cell)
organism
one individual member of a species: a living thing
organ system
set of organs working together for a common function
organ
set of tissues working together for a common function
tissue
group of cells working together for a common function
cell
most basic unit of life that has all the characteristic of life
cell cycle
a repeated pattern of growth, DNA duplication and cell division that occurs in eukaryotic cells
2 purposes in cell division
growth and repair
Interphase
the growth phase of the cell
G1: Gap 1 Phase: cell grows and makes proteins
S: Synthesis Phase: DNA Replication occurs, doubling the number of chromosomes
G2: Gap 2 Phase: more cell growth and protein synthesis
Chromosome
one long continuous thread of DNA that consists of thousands of genes and regulatory information
Gene
a section of DNA that contains the instructions for making a protein
In normal body cells, chromosomes always occur in in pair of _______ chromosomes
homologus
Homologus Chromosome
———– |
| |
| ———– |
| |
| ———– |
(next to eachother)
| ———– |
| |
| ———– |
| |
| ———– |
Chromatif
one half of a duplicated chromosome
Sister Chromatids
two identical Chromatids
know drawing
Centromere
region of the condensed chromosomes that look pinched
telomere
ends of the DNA molecule’s
X crossed chromosomes
duplicated
mitosis
the division phase of the cell cycle
in mitosis 1 cell becomes ….
2 identical daughter cells
Ptophase
-chromosomes condense and become sister chromatids (in X’s)
-nuclear membrane disappears
-spindle fibers form out of centrioles
-know drawing
Metaphase
-spindle fibers connect to the centromere of each sister chromatid
-chromosomes line up in the middle of the cell
Anaphase
-sister chromatids separate, pulling away from each other and becoming individual chromosomes
-chromatids move to opposite ends of the cell
Telophase
-chromosomes decondense and start to look like chromatin again
-nuclear membrane reforms around chromosomes at each pole
-spindle fibers break down
-cytokinesis begins at the end of telophase
Cytokenesis
the division of the cytoplasm into 2 individual cells
END RESULT: 2 identical body cells
Differentiate between cytokinesis in plant and animal cells
In plant cells- cell plate forms midway between divided nuclei and gradually develops into a cell wall.
In animal cells- forms cleavage furrows that pinches the cell into two equal parts
I-PMAT-C
interphase-prophase, metaphase, anaphase, telophase-cytokenesis
how often do cells divide?
every cell divide at a different rate based on its need
How do body cells divide?
they must stay small to maintain a high surface area to volume ratio
smaller cells are more efficiant tgan larger cells
How do body cells divide?
they must stay small to maintain a high surface area to volume ratio
smaller cells are more efficient than larger cells
What is the cell cycle controlled by?
Chemical reactions control system that starts & stops the cell cycle (proteins play a key role in this)
External signals -
signals that come from outside of the cell
Ex. Hormones, Nutrients, etc.
Internal signals -
signals that come from the cell’s own nucleus Ex. DNA inside the cell
Checkpoints
critical points where “stop” and “go” signals regulate the cycle
cell division is mostly in the ____ position in animal cells because there is no stimulus present
stop
