6 - Cell Division Flashcards
Humans have __ pairs of ______ chromosomes
23 pairs of homologous chromosomes
What are homologous chromosomes
Each code for the same thing, one is paternally inherited, one is maternally inherited
When 1 chromosome is replicated it makes _____ joined by a ____
A pair of chromatids joined by a centromere
What is a pair of chromatids?
2 identical chromosomes joined by a centromere
What is chromatin?
DNA wrapped around proteins called histones
What are chromosomes made from?
Chromatin (DNA and histone proteins)
What is a diploid?
Full set of chromosomes- 23 pairs of homologous chromosomes (pre pick and mix, di- 2 one from each parent)
What is a haploid?
1/2 a diploid, one chromosome inherited randomly from a parent (think pic and mix)
What are the 2 parts of the mitosis cell cycle?
Cell growth and cell division
What happens during cell growth in mitosis?
Interphase:
- cell grows in size
- synthesis of organelles
- DNA checking
- fuel stores
What happens during cell division stage in mitosis?
- mitosis
- cytokenesis
Name the stages of mitosis interphase in order
G1
S
G2
(then mitosis and cytokenesis)
What happens in G1 stage of interphase?
Cell contents (everything but chromosomes) are duplicated -cell grows in size
What does G1 checkpoint in interphase check for?
- DNA damage
- Cell size
- Cell nutrients
What is the G0 stage of interphase?
Cells leaving the cell cycle, either temp. or permanently, because of DNA damage or the cells are specialised
What is the S stage of interphase?
DNA replicated and sister cromatids form
What is the G2 stage of interphase?
Cell continues to grow in size
energy (ATP) stores replenished
What does G2 checkpoint in interphase check for?
- DNA damage
- Cell size
What happens after the G2 phase of interphase
Mitosis
BLURT! Draw the cell cycle for mitosis from G1 of interphase to cytokinesis (including checkpoints and the function of each stage)
Photo 1 in revision folder
Name the stages mitosis
Prophase, Metaphase, Anaphase, Telophase
State what happens in prophase in mitosis (5)
- chromosomes condense
- nuclear envelope dissolves
- nucleolus disappears
- centrioles produce spindles
- spindles from poles of cells attach to centromere
State what happens in Metaphase
Chromosomes are pulled to the centre, to the metaphase plate
State what happens in anaphase
Chromatids are separated, pulled to the poles of the cells
State what happens in Telophase
- chromatids reach poles of the cell
- nuclear envelope reappears
- nucleolus reappears
- chromosomes recondense into nuclei
What happens in cytokinesis of animal cells?
Cleavage furrow forms and cytoskeleton pulls the cell in two
BLURT! Draw the stages of mitosis in order with explainations
Revision photo 2
What are the stages of meiosis?
Prophase I Metaphase I Anaphase I Telophase I Cytokinesis
Prophase II Metaphase II Anaphase II Telophase II Cytokinesis
How many chromosomes are present in Prophase I of meiosis, what is this set called?
Diploid, 46 chromosomes (23 each with a homologous pair)
What is special about Prophase I in meiosis
Chromosomes pair up and cross over
When do chromosomes pair up and cross over
Prophase I in meiosis
What causes genetic variance in meoisis
Chromosomes pair up and cross over in meoisis I and randomly line up (independent assortment) in Metaphase I
BLURT! Draw the stages of meosis I and II in order with explainations
Picture 3 and 4 revision folder
What is different between metaphase I and metaphase II in meiosis
Metaphase I the homologous pairs are separated (one chromosome to each pole)
Metaphase II the chromatid pairs are separated (from centromere)
How many chromosomes are present in Prophase II of meiosis, what is this set called?
23, a haploid (one randomly pic and mixed from one of your parents)
What is the result of meoisis
4 genetically different daughter cells (gametes)
-haploid
Cells group together to form __
tissues that perform a common function
Organs are ___
groups of tissues that work together to form a wider function
Organ systems are ___
groups of organs that work together to perform and essential life function
What is the function of xylem?
transport minerals and water as well as providing structural support
What is the structure of xylem?
Long, open-ended tubes formed of dead tissue
What are xylem cells made by
Meristem cells
What is the function of phloem?
movement of food substances and nutrients from leaves to storage organs and growing parts of plants
What is the structure of phloem?
Long tubes made of living cells
What are phloem cells made by
Meristem cells
What are the features of cells that the meristem produces
meristem tissue
produce cells that elongate and line up end to end to form tubes
What are Epithelial cells
sheets of cells that serve as a lining or to cover a surface
What are the 2 types of Epithelial cells
- -squamous which are smooth, flat and very thin
- -ciliated, cylinder in shape and have cillia
What are the 3 types of role for cells
Connective
Muscle
Nervous
What is a stem cell?
undifferentiated cells which have the ability to
develop into any kind of cell
Discuss the differences between human and plant stem cells
Plants retain their ability to differentiate into different types of cells throughout their life
Humans do not, we can only make some particular types of cell eg. RBCs erythrocytes
Where does the division of plant cells occur at the highest rate?
Meristem
Name a specialised cell in a human and how it is specialised
Sperm cell adapted to reach, penetrate and fertilise the ovum (enzymes in head and flagellum)
What is totipotent
stem cell able to become any cell/ form a whole organism
What is pluripotent
stem cell able to become any tissue type but not a whole organism
what is multipotent
stem cell able to become only a range of cell types
What is the difference between ciliated cells and ciliated epithelium
ciliated epithelium in a tissue - a group of cells working together
ciliated cells are any single cells with cillia
Why are cells checked frequently in the cell cycle?
dna errors cell does not divide too often cell divides at right time is right size chromosomes in the right position
3 sources of sttem cells
embryos
umbilical cord
meristematic tissue
How can stem cells help treat heart disease?
repair tissue muscle in the heart damaged by heart attacks
How can stem cells help treat diabetes?
replace beta cells destroyed by immune system
How can stem cells help treat genetic diseases?
reverse previously untreatable birth defects
