Mitosis and Meiosis

Mitosis and Meiosis

By onlyfor quizzes

Multiple Select

What are the two ways cells reproduce?

• Mitosis

• Mirosis

• Meitosis

• Meiosis

Mitosis

what is mitosis

• Mitosis is cell division that happens in body cells (somatic cells).

• There are four stages: Prophase, Metaphase, Anaphase, and, Telophase (PMAT).

• ​The point of mitosis is to replicate cells in an attempt to replace dead and damaged cells

Multiple Choice

What is another name for body cells?

• Bodily cells

• Somatic cells

• Germ cells

• Gametes

what is mitosis

• When mitosis occurs a parent cell divides to create two identical daughter cells.

• Mitosis is a small part of the cell cycle.​

Multiple Choice

How many daughter cells are created from mitosis?

• 1

• 2

• 3

• 4

​MITOSIS

• The cell cycle refers to the sequence of events which occur between one cell division and

  the next.

• It includes three stages interphase, mitosis and cytokinesis

• Interphase is the longest stage and it's where cell DNA is replicated

​

​The cell cycle

Multiple Choice

What is the longest phase of the cell cycle

• Meiosis

• Mitosis

• Interphase

• Cytokinesis

interphase

Before mitosis occurs, the chromosomes (and centrosomes) are replicated which means each chromosome will have an exact copy of itself. This ensures that each daughter cell has the same number and type of chromosome as their parent cell.​

Chromo stuff

​differentiating terms

​Chromatin: Loosely coiled up strings of genes; Means coloured material.

​

Chromatid: Part of a chromosome, like a half.

​

Chromosome: A condensed/fat chromatin, that is more tightly coiled. Chromo thing that is a part of cell division​ in the beginning

Multiple Choice

What chromo thing is loosely coiled strings of DNA, attached to histones?

• Chromophyl

• Chromosome

• Chromatid

• Chromatin

Multiple Choice

What chromo thing means coloured material?

• Chromophyl

• Chromosome

• Chromatid

• Chromatin

Multiple Choice

What chromo thing is tightly coiled and condensed strings of DNA, attached to histones?

• Chromophyl

• Chromosome

• Chromatid

• Chromatin

Multiple Choice

What chromo thing is half of a chromosome?

• Chromophyl

• Chromosome

• Chromatid

• Chromatin

Chromosomes

​

• The centromere is the central part of the chromosome that connects two chromatids.

• Chromosomes are counted by the number of centromeres and not by the number​ of chromatids.

• When chromosomes replicate in interphase ​they make two chromatids, joined by a centromere. These chromatids (and centromere) are split up in mitosis and make their own chromosomes for the daughter cells created

chromosomes

• Every somatic cell in humans has 46 chromosomes; 23 pairs.

• The basic structure of chromosomes is the same in all animals

• The number of chromosomes in the somatic cell of any animal is called their diploid number; It is represented as 2n, 'n' being the number of pairs.

​Structure and number

chromosomes

• Diploid number in humans: 2(23)

• 'n' also means the haploid number in germ or reproductive cells (gametes)

• The haploid number is the number of chromosomes in the gametes of any organism

​Organisms, like plants, with 3+ sets of chromosomes are polyploid.

​Structure and number

Multiple Choice

Which term does not mean sex cells?

• Gametes

• Germ cells

• Reproductive cells

• Somatic cells

Multiple Choice

What is the germ cell in women?

• Ovary

• Ovule

• Testes

• Sperm

Multiple Choice

What is the gamete in men?

• Ovary

• Ovule

• Testes

• Sperm

Centro stuff

• Centromere: Joins 2 chromatids; At the center of a chromosome. The centromere is the region that becomes associated with microtubules of the spindle.

• Centriole: Poles that extend microtubules to move/manipulate chromosomes, Plant cells don't have these.

• Centrosome: Attached to a cell's nuclear envelope and is in the cytoplasm. It holds 2 centrioles at a right angle. Also called the microtubule organizing center (MTOC).

Spindles are the structure formed from microtubules extending from centrioles

Multiple Choice

What centro thing is attached to a cell's nuclear envelope?

• Cetromere

• Centrosome

• Centrometer

• Centriole

Multiple Choice

What centro thing is positioned to form a right angle?

• Cetromere

• Centrosome

• Centrometer

• Centriole

Multiple Choice

What centro thing is also known as the MTOC?

• Cetromere

• Centrosome

• Centrometer

• Centriole

Multiple Choice

What centro thing holds chromatids together?

• Cetromere

• Centrosome

• Centrometer

• Centriole

chromosome

Multiple Choice

Chromosomes similar in structure are _______

• Heterologous

• Translogous

• Bilogous

• Homologous

Multiple Choice

Autosomes are non-sex chromosomes

• True

• False

Multiple Choice

How many pairs of autosomes do humans have

• 21

• 22

• 23

• 24

Chromosomes

​why do we have 23 pairs of chromosomes?

• Each pair of chromosomes comes from a parent. 23 chromosomes are from the mother and 23 chromosomes are from the father​.

• When 2 haploid cells come together (the sperm fertilizing the egg) a diploid cell is formed (zygote)​.

​x chromosomes (from mother or father), are longer and contain more DNA than y chromosomes (from father)

Mitosis

​Prophase

• The longest phase of division.

• In prophase, the chromosomes are coiled and condensed

• The mitotic spindle forms

• The nucleolus shrinks and disappears

• The nuclear envelope dissolves or breaks down (disintegrates)

• The chromosomes are now visible as they are coiled and condensed.

• Each chromosome consist of two (2) chromatids joined by the centromere (2

  chromatids identical in structure and genetic information).

MItosis

​Metaphase

• Chromosomes line up on the equator of the cell. This means all

chromosomes are now located on equatorial plane.

• Spindles attach to centromeres​

MItosis

​anaphase

• The shortest phase of mitosis

• Sister chromatids separate

• Centromeres divide

• Sister chromatids move to opposite poles using the spindle as a roadway or guide.​

MItosis

telophase

• The cell enters telophase when all the daughter chromosomes have reached their opposite poles.

• Spindle fibers and microtubule start to break down and disappear

• Chromosomes uncoil • now chromatin

• Nuclear membranes and nucleoli start to reform​

cytokinesis

​Is the physical process of cell division, which divides the cytoplasm

of a parental cell into two daughter cells.

• Occurs at end of Mitosis

• Division of the cytoplasm to form 2 new daughter cells

• Organelles are divided

• Daughter cells are genetically identical

Multiple Choice

Chromosomes are aligned to be in the center of the cell

• Prophase

• Metaphase

• Anaphase

• Telophase

Multiple Choice

Chromosomes swell and nuclear membranes break down.

• Prophase

• Metaphase

• Anaphase

• Telophase

Multiple Choice

Nuclear membranes and nucleoli reform

• Prophase

• Metaphase

• Anaphase

• Telophase

Multiple Choice

Centromeres split and are pulled to opposite ends of the cell

• Prophase

• Metaphase

• Anaphase

• Telophase

Multiple Choice

Cytoplasms divides

• Prophase

• Cytokinesis

• Anaphase

• Telophase

examples of asexual reproduction

• Binary fission

• Vegetative propagation

• Cloning​

meiosis

Multiple Choice

Where does meiosis take place?

• Only in sex cells

• Only in body cells

• In both sex and body cells

• Only in humans

Meiosis

• Meiosis is cells division that only takes place in sex cells

• When meiosis happens, 4 daughter cells are created from a parent cell; These daughter cells are not gentically identical.

• The daughter cells created from meiosis has half the number of chromosomes as the parent cell; The cell divides twice but only replicates its DNA once

• The daughter cells are not genetically identical so there can be variation in the offspring

Multiple Choice

How many daughter cells are formed in meiosis

• 1

• 2

• 3

• 4

Multiple Choice

Daughter cells formed in meiosis are genetically identical

• True

• False

Multiple Choice

Human germ cells are

• Polyploid

• Triploid

• Diploid

• Haploid

meiosis

• It occurs within the formation of eggs/ovules in women, sperm in men, and spores in some plants.

• Meiosis is continuous and divided into two prophases, two metaphases, two anaphases , and two telophases (also two cytokinesis).

The formation of sex cells in humans is called gametogenesis​

Multiple Choice

Two homologous chromosomes come together in meiosis, forming a _____

• bivalent

• divalent

• trivalent

• tetravalent

meiosis

​Homologous chromosomes

• Homologous chromosomes are basically two similar chromosomes inherited from father and mother. They are homologous because they have the same gene, but different alleles.

• Homologous chromosomes pair up to form bivalents, also known as a tetrad.​

meiosis

​Chiasmata/crossing over/recombinattion

• Homologous chromosomes pair up and so a tetrad or bivalent is now formed.

• Chromatids now visible. They may cross over.

• Chromosomal crossover (or crossing over) is an exchange of genetic material between homologous chromosomes. Crossover usually occurs when matching regions on matching chromosomes break and then reconnect to the other chromosome.

• Chromosomes are joined at several places along their length (chiasmata).

meiosis

​chiasmata/crossing over/recombination

• Each chiasma (singular) is the site of an exchange between chromatids. Chiasmata (plural) are X-shaped portions formed between adjacent chromosomes.​

• ​As a result, genes from one chromosome may swap with genes from the other chromosome leading to new gene combinations in the resulting chromatids.

Multiple Choice

Which is not a term for chromosomal crossover

• Chiasmata

• Chiasm

• Recombination

• Crossing Over

Multiple Choice

Chiasmata switches genes between chromosomes from each parent, diversifying the different chromatids

• True

• False

meiosis

prophase i

• Duplicated centro​somes move to either side of the cell

• Chromosomes condense​

• Nuclear membrone and nucleolous break down​

• Homologous chromosomes form bivalents and recombine

meiosis

​metaphase i

• The chromosomes are connected to the microtubules and chromosomes migrate and meet at the equatorial plane (they line up).

• The chromosomes are still held together by chiasma.

meiosis

​anaphase i

• Homologous chromosomes separate. That is, the bivalents separate and move away from each other towards opposite centrosomes.

• Centromeres do not split!!!!​

meiosis

​telophase i

• The chromosomes arrive at opposite ends of the cell.

• A nuclear membrane forms around each group.

• Spindle fibres break down.

• For some organisms including humans cytokinesis normally follows telophase. That is, the parent cell divides into two daughter cells.​

meiosis

​Cytokinesis i

• ​Cytoplasm splits

• Two daughter cells are formed

meiosis

interphase ii

• Centriole is duplicated in both daughter cells​

meiosis

prophase ii

• Centrioles move to opposite sides of the cell

meiosis

metaphase ii

• Chromosomes line up at the equatorial plane

meiosis

anaphase ii

• Chromatids and centromeres split and move to opposite ends of the cell.​

meiosis

telophase ii

• Chromatids arrive at opposite ends or poles.

• Nuclear membrane reforms around chromosomes​

meiosis

cytokinesis ii

• Cytoplasm splits​ and 4 new dauter cells are formed

Multiple Choice

Chiasmata happens

• Prophase I

• Prophase II

• Metaphase I

• Metaphase II

Multiple Select

Two daughter cells are formed

• Mitrosis

• Meiosis I

• Mitosis

• Meiosis II

Multiple Choice

Chromosomes are pulled to opposite spindle poles

• Metaphase I

• Metaphase II

• Anaphase I

• Anaphase II

Multiple Select

Chromosomes line up at equatorial plane

• Metaphase I

• Metaphase II

• Anaphase I

• Anaphase II

Multiple Select

New nuclear membranes and nucleoli form

• Telophase I

• Telophase II

• Cytokinesis I

• Cytokinesis II

Multiple Choice

Chromatids are pulled to opposite spindle poles

• Metaphase I

• Metaphase II

• Anaphase I

• Anaphase II

Multiple Select

Cytoplasm splits and makes 2 new daughter ce

• Telophase I

• Telophase II

• Cytokinesis I

• Cytokinesis II

Multiple Choice

Cytoplasm splits and makes 4 new daughter cells

• Telophase I

• Telophase II

• Cytokinesis I

• Cytokinesis II