12 Cell Cycle Flashcards
Mitosis
“thread,” chromosomes condense into compact structures that can be moved around the cell efficiently then one copy of each chromosome is distributed to each of two daughter cells
Chromosome
“coloured body,” thread-like structures consisting of a single long DNA double helix wrapped around proteins called histones in a highly organized manner
Gene
a region of DNA in a chromosome that codes for a particular protein or ribonucleic acid
Centromeres
DNA region that functions as a handle on a chromosome
M phase (Mitotic or Meiotic)
Cells are in the process of separating their chromosomes
Interphase
Cells are either growing and preparing to divide or fulfilling its specialized function in a multicellular individual; Chromosomes are loosely dispersed in the nucleus
When does DNA replication occur?
S (Synthesis) phase in the Interphase
Cell Cycle
Orderly sequence of events that leads a eukaryotic cell through the duplication of its chromosomes to the time it divides
What happens in gaps 1 and 2 in the cell cycle?
Cells grow and replicate organelles so it will be able to divide into two cells that can function normally
Chromatins
DNA-protein (histone protein) complex which form chromosomes within an interphase nucleus
Cohesins
Large number of protein rings at the centromeres that hold sister chromatids together until a signal is given and they become independent chromosomes
Kinectochores
site where microtubules (in the cytosol) connect to chromosomes by forming an interface between chromosomes and inside of nuclear envelope
Condensins
ring-shaped proteins along the length of chromosomes that compact them for mitosis; encircles DNA and stabilizes loops in the same piece of DNA
What 5 proteins does DNA work with in mitosis?
cohesins, microtubules, kinetochore, nuclear lamins, condensins
What are the 5 subphases within M phase?
prophase, prometaphase, metaphase, anaphase, telophase
Centrosomes
located in animal and fungal cells, microtubule-organizing centres or large protein complexes that contain small bundles of microtubules known as centrioles
Prophase
When chromosomes condense into compact structures, marked by the formation of spindle apparatus
Spindle apparatus
Consists of distinct populations of microtubules anchored at their base to a centrosome (in an animal cell) or NEDD1 complex (in a plant cell)
What does a spindle apparatus do?
Produces mechanical forces that (1) pull chromosomes to the poles of the cell during mitosis and (2) push the poles of the cell away from each other
Types of spindle apparatus
polar, kinetochore, astral
Polar microtubules
extend outwards and overlap with other polar microtubules attached to the opposite MTOC
Kinetochore microtubules
proteins at the centromeres that hold the DNA and microtubules together
Astral microtubules
found only in animal cells and connect the centrosome to proteins on the inner surface of the plasma membrane
Prometaphase
Nuclear envelope begins to disappear and chromosomes move to the middle of the cell after kinetochores attach to microtubules
