[Unit 2.2] Cells Arise From Other Cells Flashcards
Cells
definition of tissue
collection of cells perform specific function
e.g xylem
definition of organ
combination of tissues coordinated for a particular function
definition of organ system
organs work together performing a complex function
definition of organism
organ systems working together to perform a variety of functions to create a living thing
what is cell differentiation
The process in which cells become specialized for different functions
how do cells become specialised
chemical compositions in cytoplasm controls which genes are expressed
definition of supercoiling
wrapping up DNA. with histones
cant be transcribed
-off
definition of uncoiled
not wrapped by histones.
can be transcribed
-on
what are the (5) stages of mitosis
prophase, metaphase, anaphase, telophase, cytokinesis.
Note that cytokinesis is technically after mitosis.
Mitosis is the two nuclei forming only.
What happens during the prophase
chromosomes coil (become more visible)
nuclear envelope & nucleolus breaks down
spindle starts to form
What happens during the metaphase
chromosome align at the equator of the cell (very visible)
attached to spindle by centromere
What happens during the anaphase
spindles shorten, pulling centromere towards poles
chromatids separated into two daughter chromosomes
What happens during the telophase
chromosomes lengthen (less visible)
nuclear envelope and nucleolus reappear
What happens during cytokinesis
other cell organelles are evenly distributed around nucleus
cytoplasm starts to divide
What happens during the interphase
-cell becomes larger
-organelles double
-extra protein synthesis (for spindles)
-DNA replication
what are the 4 stages of binary fission
1) circular DNA (once) & plasmids (many) replicated
2) cell elongates. DNA moves to opposite poles
3) cytoplasm divides, new cell wall and membrane form
4) cytoplasm finishes dividing, 2 genetically identical daughter cells
similarities between mitosis and binary fission.
-both cells must grow before dividing
-both produce two genetically identical daughter cells
-one set of chromosomes each
-cytoplasm splits
differences between mitosis and binary fission.
-DNA doesn’t line up at equator of cell in binary fission
-Fewer chromosomes
-Binary fission is a quicker process
how does a tumour form
mutation in proteins that regulate cell cycle leads to uncontrolled division
what is a tumour
large mass of abnormal cells due to uncontrolled division
what is the difference between malignant and benign tumour
malignant spreads to other tissues in the body, benign does not
how does chemotherapy treat cancer
targets g1 phase. enzymes needed for DNA replication are made in G1. So cell cant enter S phase. So destroys itself
how does radiotherapy treat cancer
targets S phase. DNA gets damaged by radiation. cell detects that DNA is damaged and destroys itself.
what are the three stages of the cell cycle
mitosis, cytokinesis, interphase (90% of time)
what are the three stages of interphase
G1, S, G2
what happens during the G1 phase
cell growth, new organelles and proteins made
what happens during the S phase
DNA replication
what happens during the G2 Phase
cell keeps growing, proteins for cell division are made
what and where are the checkpoints during interphase
inbetween each phase the DNA is checked for errors so the daughter cells do not contain the same mutation
what is karyokinesis
splitting of the nucleus
when does karyokinesis occur
during mitosis and meiosis
what happens, with an example, when karyokinesis occurs without cytokinesis
a multinucleated cell is formed such as a muscle cell
