Cell Division for Development, Growth, and Maintenance in Multicellular Organisms (Mitosis) Flashcards
What are three main reasons for which cells need to divide?
reproduction, development (including growth), maintenance
What does maintentance involve?
repairing damage, tissue renewal…
What is growth?
increase in number of cells
What are ways cells develop other than growth?
differentiation, morphogenesis…
What is the difference between stem cells and most other cells?
most cells differentiate while stem cells don’t
What happens when a cell differentiates?
becomes specialized, develops into a certain type of cell
What makes a cell lose the ability to become other kinds of cells?
differentiation
What cells remain plastic?
stem cells
What does “plastic” mean in terms of cells?
ability to generate different types of cells
What are two special characteristics of stem cells?
self-renewal and potency
What does self-renewal mean?
cells continue to divide and divide without differentiating
What is potency?
capacity to produce cells that differentiate into specific cell types
What is an extreme case of tissue renewal?
limb regeneration in animals
What are some animals that can regenerate their limbs?
starfish, crabs, salamanders
What are the 4 types of stem cells?
- totipotent
- pluripotent
- multipotent
- unipotent
What types of cells can totipotent stem cells form?
any cell in the body
What type of stem cell can only form one type of tissue?
unipotent
What can pluripotent stem cells form?
most types of tissues
What can multipotent stem cells make?
certain types of tissues
What are some examples of totipotent stem cells?
- fertilized egg
- cells from very early embryo (4 days old)
Where can pluripotent stem cells be found?
embryo
Where can multipotent stem cells be found?
- bone marrow
- amniotic fluid
What type of stem cells is found in the skin and the liver?
unipotent
What do eukaryotic cells contain that complicate cell division?
- nuclear membrane
- organelles
- multiple chromosomes
WHAT IS A COMPLETE ARRAY OF CHROMOSOMES CALLED?
(answer - genome? karyotype?)
What is the term for the physical map of a complete array of chromosomes?
karyotype
What are 2 chromosomes of the same type called?
homologous
What does homologous mean?
contain the same genes
When are eukaryotic chromosomes duplicated?
before division
What are the 2 kinds of cells in eukaryotes?
somatic and sex cells (gametes)
What is the main difference between somatic cells and sex cells?
contain different number of chromosomes
sex cells are haploid while somatic are diploid
How many chromosomes are in a human somatic cell?
46
If a cell has 36 chromosomes, what is 2N? N?
2N = 36 (diploid number) N = 18 (haploid number)
How many sets of chromosomes are in somatic cells?
23 pairs - 2 sets
What does diploid mean?
having 2 sets of chromosomes
What are cells called when they only have 1 set of chromosomes?
haploid
How many chromosomes are in human sex cells?
23
What is the term to describe a cell with 3 sets of chromosomes? 4?
3: triploid
4: tetraploid
What is chromatin made of and in what relative quantities?
60% protein
40% DNA
What is chromatin?
an uncondensed chromosome
What is a duplex chromosome?
double-stranded
What does chromatin wrap around to form a nucleosome?
histones (small protein complexes)
SUPERCOILING QUESTION
(answer)
NUCLEOSOME QUESTION
(answer)
What do cells need to do in order to divide?
1) replicate DNA
2) replicate organelles
3) separate the DNA (and organelles)
4) divide the cytoplasm
What are chromosomes called before duplication?
single chromatid
What are sister chromatids?
2 identical chromosomes (formed by chromosome duplication)
WHAT HOLDS TOGETHER TWO SISTER CHROMATIDS?
CENTROMERE? KINETOCHORE?
What are the two overall phases of the cell cycle?
interphase and mitotic phase
Approximately how long does the cell spend in interphase?
90% of the cell cycle
What phase of the cell cycle does the cell spend 10% of the time in?
mitotic phase
What part of the cell cycle does the cell spend 50% of its time in?
S stage (synthesis)
Which cell cycle stage is most variable?
G1
