The Cell Cycle and Control

As you know cells are very small As you know cells are very small. We need __________ to help us see cells to study them. There are reasons that cells are small. Certain limitations keep a cell __________________. Instead of continually growing, when a cell grows to a certain size it _______ (reproduces). microscopes from growing too large divides

Cell Size Limitations ________-is fast and efficient over short distances, but becomes slow and inefficient as distances become larger. For example: A mitochondrion at the center of a hypothetical cell with a diameter of 20 cm would have to wait months before receiving molecules entering the cell! Diffusion

_____- DNA is responsible for coding for proteins in our cells _____- DNA is responsible for coding for proteins in our cells. The larger the cell the more protein needs it would have. The cell’s DNA could not keep up with the protein needs of a large cell. DNA proteins

__________________________- As the cell increases, the volume increases much faster than the surface area. As the cell increases it needs more _________ and has more _______ to excrete. This means it needs more plasma membrane in which to release wastes and diffuse nutrients. Surface area to volume ratio nutrients wastes

Cell Reproduction-All cells come from ______________. (Cell Theory) preexisting cells Scientists discovered that ___________, which contain DNA and proteins become darkly colored when stained, are responsible for passing genetic information from one generation to another. These chromosomes are located inside the _______ and become visible just before the cell divides. chromosomes nucleus

Before a cell divides, the DNA is unwound into _________ to carry out cell functions. chromatin

The Cell Cycle The cell cycle is the sequence of _________________ of a cell. Most of the cell's life is spent in the period of growth called _________. growth and division interphase

Following interphase, a cell enters its period of division called ______. Mitosis is broken into four phases: ________, _________, _________, and ________. After mitosis, a short period called _________ occurs in order to divide the cytoplasm. mitosis prophase metaphase anaphase telophase cytokinesis

During interphase the cell is in a resting phase During interphase the cell is in a resting phase. It carries out __________, grows, copies its DNA and makes new ________. cell functions organelles

Interphase is divided into three phases Interphase is divided into three phases. ___ phase is the first growth period of the cell, __ phase is the time to copy DNA, and ___ phase is the second growth of the cell. G1 S G2

Prophase- first phase of mitosis Chromosomes become visible Chromosomes are made of two sister _________ (B) connected by a __________ (A) Centrioles move to opposite poles of cell Spindle starts to form Nuclear membrane ____________ chromatids centromere breaks down

Metaphase- Chromosomes line up along ______ of the cell Spindle attaches to centomeres equator

Anaphase- ____________ divide Chromosomes Chromatids separate and move to opposite ______ of the cell Chromosomes sides

Telophase- Chromosomes unwind into _________ Nuclear membrane forms around chromatin chromatin

Cytokinesis- is different in plant and animal cells. In animal cells, the plasma membrane _______ in separating two new cells. This is called _________ and the fold is called the ______________. In plant cells, vesicles containing ______________ line up in the center of the cell and fuse together forming a ________. The cell plate then connects with the existing cell wall creating two new cells. pinches cleavage Cleavage furrow cell wall material cell plate

Label the cell cycle. G1 S G2 Metaphase

Results of Mitosis When mitosis occurs, __________ organisms remain unicellular-they have simply multiplied. In __________ organisms, cell division results in groups of cells that work together as _______. unicellular multicellular tissues

Tissues form ______, organs form _____________, and organ systems form __________! organisms

Control of the Cell Cycle Biologists believe that a series of ________ called cyclins control the cell’s progress during the cell cycle. There are enzymes that tell the cell when to start mitosis as well as controlling it throughout the phases. enzymes

The production of these enzymes is done by _____ The production of these enzymes is done by _____. Genes are a segment of ____ the controls the production of a protein. genes DNA

Cells can lose control of the cell cycle and start dividing uncontrollably. The results may be ______. cancer

Cancerous cells Normal cells

Meiosis

There are two types of cells in your body: 1) ___________—body cells 2) _________—sex cells (germ cells) Somatic cells Gametes

__________ cells have ½ the number of chromosomes in a species __________ cells have ½ the number of chromosomes in a species. They are designated by 1N or N. (Sex cells) What is the haploid number for humans? ___ Haploid cells 23

__________ cells have the correct number of (paired) chromosomes for a species. They are designated by 2N. (Body or somatic cells). What is the diploid number for humans? ___ Diploid cells 46

The 2 chromosomes that make up a pair are called __________ chromosomes. Each _____________ in the pair has information about the same ____. The combination they form together results in a particular trait being expressed. The process that forms new somatic cells is _______. homologous sister chromatid gene mitosis

Human sex cells in the female are the ____ cells Human sex cells in the female are the ____ cells. In the male, they are the ______ cells. Each has ___ chromosomes or the haploid number for humans. egg sperm 23

Female sex chromosomes are represented by an ___ and males are represented by a ___. Since chromosomes are paired, _____ results in a female offspring and _____ is male. X Y XX XY

The cell division that forms new sex cells is called _______. Meiosis produces ______ cells. Meiosis haploid

Meiosis is divided into two distinct parts: ________ and _________. Each ends with cell division. Meiosis I Meiosis II

Meiosis I consists of _________I, __________I, _________I, and _________I. What happens immediately after Telophase I? _________ Prophase Metaphase Anaphase Telophase Prophase II

Meiosis II consists of ________ II, _________ II, _________ II and ________ II. It occurs immediately after ________. No replication of ______occurs before prophase II. Prophase Metaphase Anaphase Telophase Meiosis I DNA

_______ reproduction does not involve the exchange of genetic material (DNA). It can be accomplished by ______ division. This reduces genetic _______ because the resulting daughter cells are _______. Asexual cellular variation identical

Bacteria reproduce by a mitotic division called _______ _______ Bacteria reproduce by a mitotic division called _______ _______. They have circular _______ that copies itself and then a new cell wall forms dividing the cell. Binary fission DNA

Other types of asexual reproduction are: _______, which is often used by fungi, and ________ __________, which is used by a lot of plants. Budding Vegetative propagation

Sexual reproduction increases _______variation within a species because it involves the exchange of _____, which is the genetic material of a species. genetic DNA

There are ____ sperm produced in meiosis of sperm cells, which is called ______________. Egg cells undergo meiosis that is called _________. It produces ___ egg cell, which receives most of the cytoplasm, and _____ small cells that are called __________. four spermatogenesis oogenesis one three polar bodies

____________ is when chromosomes do not separate correctly and offspring end up with one chromosome too many or one too few. This causes birth defects. Nondisjunction

When a gamete with an extra chromosome is fertilized by a normal gamete the result is called ________. Trisomy zygotes have an extra ______________ and they will develop into a baby with _______________. trisomy 21st chromosome Down syndrome

If a zygote is ________ a chromosome the result is called _________ If a zygote is ________ a chromosome the result is called _________. This is usually a lethal defect, but one result is called _______________, Females will have only one ___ chromosome instead of two. missing monosomy Turner syndrome X

When a whole extra set of ___________ is present in the zygote the condition is called ________. This is lethal to animals, but is desired in plants. Polyploidy leads to ___________________. chromosomes polyploidy larger flowers or fruit.