Cellular Biology Flashcards
What are the three criteria that limit cell size?
Diffusion, DNA, and Surface Area to Volume Ratio.
How does diffusion limit cell size?
Diffusion is slow and inefficient over large distances, making it difficult for nutrients to reach the center of a large cell or for waste products to be removed.
How does DNA limit cell size?
There is a limit to how quickly DNA can be copied in the nucleus and how quickly proteins can be synthesized in the cytoplasm.
How does the surface area to volume ratio limit cell size?
As a cell's size doubles, its volume increases eight times, while its surface area only increases four times. This means a larger cell needs eight times more nutrients and has eight times more waste to excrete, but has insufficient surface area to absorb or excrete them.
What is chromatin?
Chromatin is the 'ancestor' of chromosomes, consisting of DNA wrapped around histones to form nucleosomes, which then condense to form chromatin.
How does chromatin become a chromosome?
In prophase, chromatin coils up tightly to form visible chromosomes.
What is a chromosome?
A chromosome is composed of two sister chromatids joined together at a centromere, and it is where genetic material is stored.
How many daughter cells are produced from cell division?
Two daughter cells are produced from cell division.
What are the two general periods of the cell cycle?
The two general periods of the cell cycle are Growth and Division.
What period does the cell spend most of its life in?
The cell spends most of its life in Interphase.
What is interphase?
Interphase is the phase preceding mitosis where the cell spends most of its time growing, metabolizing, duplicating DNA, and preparing for cell division.
What is mitosis?
Mitosis is a four-phase cell division process.
What are the three parts to interphase?
The three parts to interphase are rapid growth and metabolic activity; DNA synthesis and reproduction; and replication of centrioles and manufacture of other needed organelles in preparation for cell division.
What are the four phases of mitosis?
The four phases of mitosis are Prophase, Metaphase, Anaphase, and Telophase.
What occurs during prophase?
During prophase, the stringy chromatin coils up into visible chromosomes, each with two sister chromatids. The nucleus and nucleolus disappear.
What are sister chromatids?
Sister chromatids are two strands of chromatin joined by the centromere to make up a chromosome.
What breaks down during prophase?
The nucleus and nucleolus break down during prophase.
What is a centromere and what is its function?
A centromere is the joining point of the two sister chromatids. Its function is to hold the sister chromatids together and help the chromosome attach to the spindle fibers.
What is a centriole?
A centriole is a small, dark cylindrical structure located outside the nucleus, made of microtubules. It plays a role in chromatid separation and is located at the poles of the spindle structure in animal cells.
What is the spindle?
The spindle is a football-shaped, cagelike structure consisting of thin fibers of microtubules.
What occurs during metaphase?
During metaphase, chromosomes attach to spindle fibers and line up at the equator of the spindle.
What happens to the chromosomes during metaphase?
The centromeres and then the chromatids attach to the middle of the spindle.
What are the spindle fibers attached to during metaphase?
Spindle fibers are attached to the centrioles on the ends, the centromeres of the chromosomes, and then the chromatids.
What happens during anaphase?
During anaphase, the sister chromatids are separated.