Unit 2 Mitosis & Cell Division Flashcards
(37 cards)
What happens in metaphase?
the centromeres of the duplicated chromosomes line up across the center of the cell. The shortest phase
Difference between chromsomes and chromatin (presense in the cell)
Chromatin - Is found throughout interphase
Chromosomes - Seen only during cell division
What are the two reasons why cells have to divide?
- The cell has more trouble moving necessary items across the cell membrane
- “DNA overload”
Explain what DNA overload means
The larger a cell becomes, the more demands the cell places on its DNA
Explain what happens to the surface and volume ratio as a cell enlarges.
In a living cell, what part of the cell represents surface area and which part of the cell represents volume?
DECREASES
Cell membrane represents the surface area
Cytoplasm represents the volume
What are some adaptations that cells have developed that allow for a greater surface area volume ratio?
If the cell gets too large, cells can divide, change shape, and slow down metabolism
Cell division occurs in two main stages. What are they?
Mitosis - division of the nucleus
Cytokinesis - division of the cytoplasm
What is the cell cycle?
A series of events that takes place as a cell grows and divides
G1
cell growth - the cell increases in size and synthesize new proteins and organelles
Cells do most of their growing in this stage
S Phase
DNA replication - new DNA is synthesized as the chromosomes are replicated
In the end, the cells contain twice as much DNA from the beginning
G2
Preparing for cell division - many of the organelles and molecules required for cell division are produced
When G2 phase ends, cell is ready to enter the M phase
Mitosis
the period after the DNA is duplicated and the cell prepares to divide - checks for errors
What is the G0 stage? Give 3 examples of cells that, once matured in the G1 phase, enter the G0 stage indefinitely.
The G0 phase is where the cells never divide. An example of this would be sperm, egg, and neuron cells, and red blood cells, cardiac cells
Cells spend most of their lifetime in what stage? What 3 phases of the cell cycle does this include?
Cells spend most of their lifetime in interphase, which consists of G1, S phase, and G2
What are the four stages of mitosis, in order?
Prophase, Metaphase, Anaphase, Telophase
What happens in prophase?
the genetic material inside the nucleus condenses and the duplicated chromosomes become visible. Nucleolus disappears, the nuclear envelope breaks down
What happens in anaphase
the chromosomes separate and move along the spindle fibers to opposite ends of the cell
What happens in telophase
chromsomes move to opposite ends of the cell and start to uncoil into chromatin again
nucleolus becomes visible in each daughter cell
nuclear envelope reforms
spindle fibers disappear
Difference between chromsomes and chromatin (structure)
Chromatin - DNA is wrapped around proteins called histones, which are bundled further (nucleosomes)
Chromosomes - Chromosomes are condensed and supercoiled chromatin fibers
Difference between chromsomes and chromatin (appearance)
Chromatin - Long, thin and loosely coiled
Chromosomes - Supercoiled, tightly would compact
Difference between chromsomes and chromatin (organization)
Chromatin - not in an organized fashion, but is spread throughout the nucleus, which makes it easier for replication and transcription
Chromosomes - Is in an organized fashion, which is necessary and helpful for cell division
Difference between chromsomes and chromatin (visualization on the microscope)
Chromatin - you can only see on a super powerful microscope (appears as “beads on a string” when stained under a ELECTRON microscope
Chromosomes - you can see under a powerful light microscope (not as powerful)
Briefly explain how six feet of DNA is packed into the nucleus of every cell of our body! Use the terms: histone, nucleosome, chromatin, loosely coiled, supercoiled
The loosely coiled DNA strand is wrapped around proteins called histones, which are bundled further, being called nucleosomes. Then, the DNA becomes super coiled into chromatin fibers.
How many chromosomes are found in human body cells? How many chromosomes are found in human sex cells (egg and sperm)?
Humans have 46 chromosomes - 23 pairs
Egg and sperm have 23 chromosomes each
