Biology- Mitosis Meosis

Asexual reproduction

individual parent divides into two genetically identical daughter cells

Sexual reproduction

two parents contribute genetic material to the offspring which is genetically unique

What are the roles of cell division?

Replacement of lost or damaged cells, growth-multicellular organisms grow and develop from single cell (fertilize egg), cell reproduction

What are genes usually carried on? (prokaryotes)

A single circular DNA molecule

What is the DNA that has a few proteins attached? (prokaryotes)

To the plasma membrane at one point

What is a nucleoid region? (prokaryotes)

DNA not bounded by membrane

What to cells divide by? (prokaryotes)

Binary fission

What happens before the binary fission divides?

An exact copy of the chromosomes is made

Why do the attachment points divide? (Binary Fission)

So the 2 new chromosomes are attached at separate parts of the membrane

When the cell elongates what also happens? (Binary Fission)

A new plasma membrane is added and the attachment points move apart

What happens when a plasma membrane and new cell wall pinch through the cell?

It separates the 2 chromosomes into two new, identical cells

What does genome mean? (Eukaryotic cell cycle and mitosis)

A cell’s total hereditary endowment of DNA

What is a genome specific to? (Eukaryotic cell cycle and mitosis)

to species

human DNA extends about 3 meters, so how is it possible to copy all of it and ensure cells get even distribution? (Eukaryotic cell cycle and mitosis)

DNA molecules are packaged into linear chromosomes which are more manageable

What are eukaryotic chromosomes made out of?

Chromatin, a combination of DNA and proteins molecules.

When do the eukaryotic chromosome in a cell finally become visible?

When cell division occurs

What is the DNA of a eukaryotic chromosome packed into?

An elaborate, multilevel system of coiling and folding.

What happens to the cell before it starts dividing? (Eukaryotic Chromosome)

The chromosomes duplicate

The process of the chromosomes duplicating create what? (Eukaryotic Chromosome)

Sister chromatids

When the cell divides what do the sister chromatids do?(Eukaryotic Chromosome)

seperate

After the sister chromatids separate what happens? (Eukaryotic Chromosome)

two daughter cells are produced

What do the two daughter cells have in common? (Eukaryotic Chromosome)

A complete identical set of chromosomes

Human somatic cells contain how many chromosomes? (Chromosome number)

46

How many chromosomes do humans reproductive cells, gametes, sperm and egg cells have? (Chromosome number)

23

How do offspring acquire genes? (introduction to heredity)

from parents by inheriting chromosomes

Why is inheritance possible? (introduction to heredity)

sperm and ova carry each parent’s genes are combined in the nucleus of the fertilized egg

What is a somatic cell?

A body cell

Gametes have a single set of _____ autosomes and a single sex chromosomes either __ or ___

22, x, y

With how many chromosomes they are haploid?

23

The equation for human life cycle

Haploid sperm + haploid ova - zygote

What does meiosis reduce?

Chromosome number

What does meiosis increase?

genetic variation among offspring

What does meiosis produce?

4 genetically different haploid daughter cells

In the first division of meiosis l what is paired?

Homologous chromosomes

While homologous chromosomes are paired what do they do?

they cross over and exchange genetic information

The homologous pairs are separate after they cross over and what happens?

two daughter cells are produced

What do chromosomes still replicate in interphase l?

a chromatin

What do duplicated chromosomes consist of in Interphase l?

2 identical sister chromatids attached by centromere

In prophase l was condenses?

chromatin

What occurs in prophase l?

Synapsis (Homologues pair)

In prophase l chromosomes seen as distance structures each chromosomes has 2 chromatide so what happens?

synapsis forms a tetrad

In prophase l sister chromatids where held together by what?

Centromeres

Late Prophase l when centriole pairs move apart what happens?

spindle fibers form

What happens when a nuclear envelope disappears? (late prophase l)

A nucleoli disperse

Homologous chromosomes pairs line up along what? (metaphase l)

along the metaphase plate

In anaphase l what seperates independently from others?

homologous chromosomes

each pole has a haploid set of chromosomes with what? (telophase l and cytokinesis)

2 sister chromatids

What happens when cytokinesis occurs simultaneously with telophase l, forming 2 haploid daughter cells? (telophase l and cytokinesis)

cleavage furrow forms in animals cell plate forms in plants'