<< Chapter < Page Chapter >> Page >
By the end of this section, you will be able to:
  • Describe the stages of the cell cycle
  • Discuss how the cell cycle is regulated
  • Describe the implications of losing control over the cell cycle
  • Describe the stages of mitosis and cytokinesis, in order

So far in this chapter, you have read numerous times of the importance and prevalence of cell division. While there are a few cells in the body that do not undergo cell division (such as gametes, red blood cells, most neurons, and some muscle cells), most somatic cells divide regularly. A somatic cell    is a general term for a body cell, and all human cells, except for the cells that produce eggs and sperm (which are referred to as germ cells), are somatic cells. Somatic cells contain two copies of each of their chromosomes (one copy received from each parent). A homologous    pair of chromosomes is the two copies of a single chromosome found in each somatic cell. The human is a diploid    organism, having 23 homologous pairs of chromosomes in each of the somatic cells. The condition of having pairs of chromosomes is known as diploidy.

Cells in the body replace themselves over the lifetime of a person. For example, the cells lining the gastrointestinal tract must be frequently replaced when constantly “worn off” by the movement of food through the gut. But what triggers a cell to divide, and how does it prepare for and complete cell division? The cell cycle    is the sequence of events in the life of the cell from the moment it is created at the end of a previous cycle of cell division until it then divides itself, generating two new cells.

The cell cycle

One “turn” or cycle of the cell cycle consists of two general phases: interphase, followed by mitosis and cytokinesis. Interphase is the period of the cell cycle during which the cell is not dividing. The majority of cells are in interphase most of the time. Mitosis is the division of genetic material, during which the cell nucleus breaks down and two new, fully functional, nuclei are formed. Cytokinesis divides the cytoplasm into two distinctive cells.

Interphase

A cell grows and carries out all normal metabolic functions and processes in a period called G 1 ( [link] ). G 1 phase    (gap 1 phase) is the first gap, or growth phase in the cell cycle. For cells that will divide again, G 1 is followed by replication of the DNA, during the S phase. The S phase    (synthesis phase) is period during which a cell replicates its DNA.

Cell cycle

This figure shows the different stages of the cell cycle. The G0 phase where the cells are not actively dividing is also labeled.
The two major phases of the cell cycle include mitosis (cell division), and interphase, when the cell grows and performs all of its normal functions. Interphase is further subdivided into G 1 , S, and G 2 phases.

After the synthesis phase, the cell proceeds through the G 2 phase. The G 2 phase    is a second gap phase, during which the cell continues to grow and makes the necessary preparations for mitosis. Between G 1 , S, and G 2 phases, cells will vary the most in their duration of the G1 phase. It is here that a cell might spend a couple of hours, or many days. The S phase typically lasts between 8-10 hours and the G 2 phase approximately 5 hours. In contrast to these phases, the G 0 phase    is a resting phase of the cell cycle. Cells that have temporarily stopped dividing and are resting (a common condition) and cells that have permanently ceased dividing (like nerve cells) are said to be in G 0 .

Questions & Answers

The major digestive gland
Jasamin Reply
salivary gland present in mouth.
Sneha
yeah it's right answer
hanuman
salivary gland present in mouth secret amylase enzyme
Fahad
The neck is _____ to the navel.
Duchess Reply
connected
FAITH
connected
Fartun
.
Rachna
cranial
Sarah
the function of pancreatic juice is
Elastus
connected/attached
Fahad
function of pancreatic juice is to break down the sugar , fats and starches
Fahad
Superior
Jerry
attached
Okonkama
distal
Susan
lateral
Susan
Describe the sequence of injuries that may occur if the extended, weight-bearing knee receives a very strong blow to the lateral side of the knee.
Dondon Reply
what is anotomy and waht is phesiology
chanbasha Reply
anatomy is classified the origin physiology is functional of origin
oHo
classified origin functional of origin
Sheryl
Anatomy is the origin of the human body Physiology is the function of the human body
Rose
Differentiate between pharmacist and apothecary
adanoor Reply
What is metatarsal
Ndotenyin Reply
bone of the foot is known as metatarsal
Patrick
yes 👆 right
Sneha
metatarsal (foot bone).....👍
Rishi
what is the meaning for cadavers
Malar
yes metatarsal are foot bone
Rakiya
the term "mental" pertain to which of the following a. chin b.navel c. ear d. nose e. skull
cris Reply
a
Lina
chin
Sneha
hi
Mohamed
skull
Monica
skull
Peter
chin
Kelly
skull
Juma
skull
Gul
skull
Laraib
skull
anwaar
skull
Nirmala
skull
Tessmol
chin
Derrick
mental chin nerve
Katarzyna
e. skull
Jennifer
skull
prince
e. skull
Natasha
It's not skull but chin
mwango
the skull
Rakiya
what are the three many components of the lymphatic system?
Milica Reply
those are...... organ, tissue and blood capillary or vessals
Juma
anatomical terms and use them appropriatly in the language of anatomy of anterior body landmarks
Teody Reply
what is human anatomy?
rascal Reply
lts stady structured human body's
Sa
what is the study of how the body functions?
Bright
What is human anatomy
Sherifat
human antomy is the body of structure
Malar
is the study of human body
Rakiya
what is abdomipelvic cavity?
david Reply
Includes all organs within the abdomen(stomach,intestines) and those from the pelvic region hence the name... abdomipelvic
Maureen
where can we find the short bones
Chidi Reply
Carpal bones are examples of short bones
Dara
what is blood supply
Chidi
on upper limb and lower limb
Juma
carpal bones
Priya
during pregnancy which would more increase size the mothers abdominal or pelvic cavity?
Nurmalyn Reply
pelvic cavity I think
Priya
What is anatomical position
Nwoye
pelvic
Maureen
@ Nwoye... when standing erect, feet parallel, arms hanging at the sides with palms facing forward
Maureen
The pelvic cavity
Rakiya
pelvic
Malar
define the main directional terms of the body
cris Reply
during physical exercise respiratory rate increace two student are discussing the mechanisms involved. student A claim they are positive feedback and student B claim negative feedback do you agree with student A or B and why
cris
what is the physiology of circulation
Chidi
please I mean the physiology of criculation
Chidi
blood flow refers to the movement of blood through the vessels from arteries to the capillaries and then to the veins
Laraib
the heart&the lungs
Rakiya
during pregnancy, which would more size the mother's abdominal or pelvic cavity? explain
cris Reply
list and define the three plane of devision of the body
cris
complete the following statements using correct directional terms for human being. 1. the navel is________to the nose 2. the heart is______to the breastbone(sternum) 3 the ankle is______to the knee 4 the ear is______to the eyes.
cris
1. superior 2. posterior 3. superior 4. lateral
Mnm
anterior fuerior
Chidi
inferior medial posterior lateral we
Susan

Get the best Anatomy & Physiology course in your pocket!





Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Anatomy & Physiology' conversation and receive update notifications?

Ask