The cell, Mitosis and Meiosis

The cell theory tells us that

1) All living things are made of cells

2) Cells are the basic unit of structure and function

3) All cells come form pre-existing cells

prokaryotes lack

lack membrane bound organelles

circular genome

Eukaryotes have

nucleus and membrane bound organelles

Cytoplasm is

everything within the cell including the organelles, but not the nucleus.

Cytosol is:

the liquid found inside of a cell

Cytoskeleton is

a mesh of proteins

Microtubules

provide structure and shape to a eukaryotic cell

intermediate fillaments

robe-like cytoskeletal like kertin

Microfilaments

Fine, threadlike proteins found in the cell's cytoskeleton

Cytoskeleton Function

cell shape, connect cells, transport, movement

Nuclear envelop

double membrane that surrounds a cell nucleus

Smooth Endoplasmic Reticulum

Makes lipids and breaks down toxins

Vesicles

small membrane sacs used for storage and transport

Golgi apparatus

packages proteins into vesicles

Lysosomes

Hydrolysis and waste disposal and digestion

what happens in prophase of mitosis?

-DNA condenses

-Nuclear evelope begins to dissolve

what happens in prometaphase of mitosis?

-Nuclear envelop dissapears

-mitotic spindle forms

what happens in metaphase of mitosis?

Chromosomes line up in the middle of the cell

what happens in anaphase of mitosis?

sister chromatids separate

what happens in telophase of mitosis?

Nuclear Envelope reforms, Chromosome Uncondensed,

what happens in cytokinesis of mitosis?

division of the cytoplasm

Cyclin dependent kinases are ?

are enzymes that control progression through the cell cycle.

telomeres are

repeating noncoding sequences at the ends of each chromosomes

What happens during Interphase?

Cell grows

Performs normal functions

Prepares for division

DNA is replicated

Stem cells are

cells that can turn into other types of cells and can self-renew

Progenitor cell

cells that can turn into other types of cells and can NOT self-renew

What are the types of stem cells

totipotent, pluripotent, multipotent, unipotent

Totipotent stem cell

A stem cell able to develop into any type of body cell.

pluripotent stem cells

Stem cells that can become almost all types of tissues and cells in the body.

multipotent stem cells

Can only become select types of cells

Unipotent stem cell

A stem cell that can only differentiate into one type of cell.

what are the sources of stem cells

Embryonic stem cells , adult stem cells , induced pluripotent stem cells (iPS cells)

Embryotic stem cells

Pluripotent

Adult stem cell

multipotent or unipotent

induced pluripotent stem cells (iPS)

stem cells derived from adult tissues

What is a homologous chromosome ?

chromosome pairs that contain the same genes but possibly different alleles

what happens in prophase I

crossing over

Metaphase I

independent assortment

What is cell theory?

All living things are made of cells

What is the basic unit of life?

The cell

Where do new cells come from?

From existing cells

What are the two main types of cells?

Prokaryotic and Eukaryotic

What do phospholipids have?

Hydrophilic head and hydrophobic tail

How many divisions happen in meiosis?

two

How many cells are made in mitosis?

4 cells

Are meiosis cells identical?

No

What does crossing over do?

Mixes genetic material

What is spermatogenesis?

Making sperm

What is oogenesis?

Making eggs

Where is sperm made?

Testes

Where are eggs made?

Ovaries

When does spermatogenesis start?

At puberty

What is a spermatogonium?

Diploid starting cell (2n)

What happens to spermatogonium?

Mitosis → primary spermatocyte

What is a primary spermatocyte?

Diploid cell (2n) before meiosis I

What happens in Meiosis I?

Primary spermatocyte → two secondary spermatocytes

Are secondary spermatocytes haploid or diploid?

Haploid (n)

What happens in Meiosis II?

Secondary spermatocytes → spermatids

How many spermatids are formed?

Four

What changes during spermiogenesis?

Tail forms, head forms, excess cytoplasm removed

How many sperm are made from one primary spermatocyte?

Four sperm

Where does oogenesis happen?

Ovaries

When does oogenesis begin?

Before birth

What is an oogonium?

Diploid starting cell (2n)

What does oogonium become?

Primary oocyte

When does primary oocyte stop?

Prophase I (before birth)

When does meiosis continue?

At puberty (each cycle)

What happens in Meiosis I (oogenesis)?

Primary oocyte → secondary oocyte + polar body.

Is division equal in oogenesis?

No, unequal division

What is a polar body?

Small cell with little cytoplasm

Is the secondary oocyte haploid or diploid?

Haploid (n)

When does Meiosis II stop? (oogenesis)

Metaphase II

When does Meiosis II finish?

Only if fertilization happens

What is produced after Meiosis II?

One ovum + polar bodies

Is division equal in spermatogenesis?

Yes

What does the head of a sperm contain?

Nucleus and acrosome

What is the nucleus in sperm?

Contains the genome (DNA)

What is the acrosome?

Cap on the head

What does the acrosome contain?

What do acrosome enzymes do?

Help sperm enter the egg

What is in the midpiece of a sperm?

Mitochondria

What do mitochondria do in sperm?

Provide energy (ATP)

Why does sperm need energy?

To swim

What is the tail of a sperm made of?

Flagellum

What does the flagellum do?

Movement

What surrounds the egg cell? (ovum)

Corona radiata and zona pellucida

What is the corona radiata?

Outer protective layer of cells

What does the corona radiata do?

Protects and nourishes the egg

What is the zona pellucida?

Protective glycoprotein layer

Where is the zona pellucida located?

Under the corona radiata

What does the zona pellucida do?

Protects egg and binds sperm

What happens to the zona pellucida after fertilization?

Hardens to block other sperm

What is a polar body?

Small cell from meiosis.

Does a polar body become an egg?

No

Why are polar bodies made?

To remove extra chromosomes.

Where does fertilization usually occur?

Fallopian tube.

What happens when sperm reaches the egg?

Acrosome reaction occurs

What does the acrosome release?

Enzymes

What do these enzymes break down?

Corona radiata and zona pellucida

Why does sperm break down these layers?

To enter the egg