Chapter 6 - Cell Continuity And Division Flashcards
All cells develop
From pre-existing cells
3 steps to form a new cell
- Produce cells it will need
- grow larger
- reproduce to for a new cell
How many chromosomes do humans have?
46
Each chromosome has how many genes?
1000s
What are chromosomes made of?
Made of DNA and protein
Where are chromosomes located?
In the nucleus
When chromosomes are not dividing what are they called?
Chromatin
How many sets of chromosomes does a diploid cell have?
Two sets
I.e. It has two of each type of chromosome in the nucleus
How many sets of chromosomes do haploid cells have?
On set
I.e. It has only one set of each type of chromosomes in the nucleus
How are chromosomes grouped in diploid cells?
Chromosomes are in pairs in diploid cells called homologous pairs
How are diploid cells symbolised?
2n
How are haploid cells symbolised?
n
How are the total number of chromosomes in a human diploid cell given?
2n=46
How are the total number of chromosomes in a human haploid cell given?
n=23
Cell cycle
The life cycle of a cell
In eukaryotic cells, what are the stages of the cell cycle?
- interphase
- mitosis
What happens during interphase?
- 90% of the cell cycle
- cell grows, replicated its organelles and duplicates its DNA
During interphase DNA is in the form of….
Chromatin
What is mitosis?
A form of nuclear division in which one nucleus divides to form two nuclei, each containing identical sets of chromosomes, creating two new cells called daughter cells which are identical to each other
What does ‘passed my algebra test’ stand for?
The four stages of mitosis
- prophase
- metaphase
- anaphase
- telophase
Three parts of prophase
- chromosomes contract and become visible as a duplicated strand
- fibres appear in cytoplasm
- nuclear membrane starts to break down
How are the total number of chromosomes in a human haploid cell given?
n=23
Cell cycle
The life cycle of a cell
In eukaryotic cells, what are the stages of the cell cycle?
- interphase
- mitosis
What happens during interphase?
- 90% of the cell cycle
- cell grows, replicated its organelles and duplicates its DNA
During interphase DNA is in the form of….
Chromatin
What is mitosis?
A form of nuclear division in which one nucleus divides to form two nuclei, each containing identical sets of chromosomes, creating two new cells called daughter cells which are identical to each other
What does ‘passed my algebra test’ stand for?
The four stages of mitosis
- prophase
- metaphase
- anaphase
- telophase
Three parts of prophase
- chromosomes contract and become visible as a duplicated strand
- fibres appear in cytoplasm
- nuclear membrane starts to break down
What happens in metaphase?
- the nuclear membrane is fully broken down
- chromosomes thicken even more
- spindle fibres attach to the chromosomes at the centromere
- chromosomes line up across the centre of cell at the equator
- each chromosomes has 2 spindle fibres attached, one from each side of the cell
What happens during anaphase?
- tribes contract, chromosomes pull apart
- strand is pulled to opposite end of cell (pole)
What happens during telophase?
- nuclear membrane forms around each of the chromosome sets
- chromosomes elongate within the nucleus and mitosis is complete
What is cytokinesis?
How the cell divides into two daughter cells after mitosis is complete
Describe cytokinesis in animal cells
- contractile, pinching the cell into two parts
- the pinch crease is called the cleavage furrow
Describe cytokinesis in plant cells
- their cell wall is too stiff to be pinched into two cells
- a line of vesicles containing cellulose form a cell plat down the centre of the cell, creating two daughter cells separated by a new wall
Vesicles
Building blocks for a cell plate which divides a plant cell after mitosis, containing cellulose
What is a cell plate?
The new cell wall formed between the two new daughter cells after plant mitosis
Function of mitosis in unicellular organisms
-a form of reproduction
Functions of mitosis in multicellular organisms
- produces new cells not new individuals
- responsible for growth and renewal and repair of cells
What is cancer?
-A disorder where the cells lose their ability to control
•the rate of mitosis and
•the number of times mitosis takes place
The rate of cell division is usually …
Carefully controlled
Benign tumours
- “kind”
- not life threatening
- do not invade other tissues
- cells stop dividing after some time
eg. Warts and skin tags
What are Malignant tumours?
- uncontrolled multiplication of abnormal cells
- invade other cells and move around the body
- cancer cells divide indefinitely
What is mestastasis?
Movement of malignant tumours invading other cells and around the body
Oncogenes
Cancer causing genes
What are carcinogens
Cancer causing agents eg. Cigarette smoke, asbestos fibres, ultraviolet radiation and some viruses
Possible cures for cancer
- Radiation (burn out cancer)
- Chemotherapy (chemicals slow down mitosis)
- Surgery
Gametes
Sex cells
Eg. Egg and sperm
What is meiosis?
Form of cell division where one cell divides into four with each new daughter cell containing half the number of chromosomes as the parent cell
Two functions of meiosis
1) Allows sexual reproduction without increasing the number of chromosomes in the offspring
2) Allows for new combinations of genes
