Biology terms

Terms / Definitions

1) What is 'The Cell Cycle= ………………………an orderly set of stages that occur between rounds of cell division
Parent cell and daughter cell
Two main phases:
Interphase: getting ready for division
Mitosis/cytokinesis: division
For cell division to occur:
Cell grows larger
Number of organelles doubles
Amount of DNA doubles
2) Interphase= Most time in cell cycle is spent here
Cell performs all of its normal functions
Time in interphase varies based on cell type
Embryonic cells: a few hours for entire cell cycle
Adult mammalian cells: ~20 hours
Neurons and muscle cells: none! (stay in G0)
Divided into 3 stages:
3) Mitosis …
4) Cytokinesis …
5) G1 Stage= First growth stage. Cell recovers from cell division, cell increases in size, doubles it's organelles, and prepares for DNA replication
6) S Stage= part of interphase where the cell copies or replicates it DNA
7) G2 Stage= Final stage before actual cell division
Make sure enough organelles and cytoplasm to make 2 daughter cells
8) Apoptosis= Programmed cell death"
Series of events, initiated by the cell, to self-destruct
9) Caspases: family of proteins that control apoptosis
Caspases= a family of proteins that regulate cell death (apoptosis).
10) The Importance of Apoptosis= Normal balance between cell division and apoptosis
Maintain correct number of cells in our bodies
Correct development (ex: our webbed fingers)
Apoptosis normally occurs:
Kill abnormal cells (which could become cancerous)
Kill virally infected cells
11) DNA Definitions Forms of DNA:
Chromatin: DNA in cells that are not actively dividing
Appearance: "tangled mass of thin threads"
Chromosomes: tightly coiled and condensed DNA in cells that are dividing
Diploid (2N) versus haploid (1N):
Diploid: two copies of each chromosome
Haploid: one copy of each chromosome (sperm/egg)
12) Diploid 2N= The regular number of chromosomes in a body cell. For humans this is 2N = 46 chromosomes or 23 pairs of chromosomes., The total number of chromosomes in a diploid cell
13) Haploid 1N= Half the number of chromosomes found in a regular body cell. This is the number of chromosomes found in sperm and egg cells. This is N- 23 chromosomes (NO PAIRS!) in humans.
14) sister chromatids = Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.
15) Centromere …
16) Kinetochore …
17) Centrosome …

18) Phases of Mitosis (must know)= Prophase, Metaphase, Anaphase, Telophase
19) Prophase= first and longest phase of mitosis, during which the chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus
20) prometaphase= The second stage of mitosis, in which discrete chromosomes consisting of identical sister chromatids appear, the nuclear envelope fragments, and the spindle microtubules attach to the kinetochores of the chromosomes.
21) Anaphase= third phase of mitosis and of meiosis I and II, in which the sister chromatids separate and move toward the poles of the spindle.
22) Telophase= fourth and final phase of mitosis, during which the chromosomes begin to disperse into a tangle of dense material (example xmas lights)
23) metaphase= second phase of mitosis, during which the chromosomes line up across the center of the cell
24) Cytokinesis plant cells= a cell plate forms in a plant cell and eventually divides the cell in 2
25) Importance of Mitosis= Main functions: growth and repair!
Single cell develops into individual (embryo → adult)
Must repair or replace damaged tissue
26) When Cell Cycle Gone Wrong? = Cancer!
27) Cellular growth disorder= when cells divide uncontrollably
Many different mutations can cause this to happen!
Cancers vary greatly and most happen gradually:
Benign: abnormal cell growth
Malignant: cancerous, can spread
28) Characteristics of Cancer Cells
a.Have rapid or continuous cell division, nearly continuously
b.Do not respond to signals for apoptosis
c.Show anaplastic morphology
w/o shape or differentiation
-usually small and round, esp the more malignant
d.Have a large nuclear-cytoplasmic ratio nucleus is larger
e. Lose some or all differentiated functions
-lose some or all of fxns, lose appearance of parent cell
f. Adhere loosely together
g.Are able to migrate
-migratory b/c not bound together
-many enzymes on cell surfaces, slip thru blood vessels and tissues
-able to spread from main tumor site to other body sites
h.Grow by invasion
-invasion and persistent growth make untx cancer cells deadly
i.Are not contact inhibited
j.Are aneuploid
-aneuploid: lose or gain chromosomes, can have more or less than 23 pairs
29) Metastasis= ability to spread to other areas of body,
read of cancer cells beyond their original site in the body
30) Angiogenesis formation of new blood vessels to supply tumor with oxygen and nutrients, The formation of new blood vessels, the process through which the tumor supports its growth by creating its own blood supply
Proto-oncogenes Genes that normally promote cell cycle;
Normal cellular genes that are important regulators of normal cellular processes, they promote growth. alterations in the expression of these cells result in oncogenes
Tumor suppressor genes Genes which code for proteins that suppress tumor formation by applying brakes on cell proliferation. (mutation that creates a deficiency would contribute to carcinogenesis) example on [p53 is a protein type] (involved in over half of human cancers!)
oncogene a gene that causes normal cells to change into cancerous tumor cells, Cancer causing gene
asexual reproduction …
Binary fission …
Prokaryotic Cell Division prokaryotes divide by binary fission, splitting into 2 nearly equal halves; prokaryotic DNA (circular, double stranded) attache to inside of cell membrane; replication begins at the replication origin; one copy of each circular DNA ends up in each daughter cell
Unicellular Organisms Prokaryotes, protists, some fungi
Use cell division for (asexual) reproduction
If entire organism is one cell, when you make another cell, you're making an entire organism!
Multicellular Organisms Some fungi, plants, animals
Cell division is part of growth, development, repair
chapter 31 chapter 31
Tissue Types Epithelial : shapes and layers
Connective: fibrous, supportive, fluid
Muscular: skeletal, smooth, cardiac
Nervous: neurons and neuroglia
Epithelial tissue Tissue that covers the surface of the body and lines the internal organs
Connective tissue
Classification of Epithelium …
Classification of Epithelium by number of cell layers and classification by cell shapes:, Classification based on cell shape
-Squamous (Flat)
-Cuboidal (Cube)
-Columnar-rectangular, pillar-like column cells
-Pseudostratified columnar
Simple Squamous single layer of flat cells, found in the lungs, lining of heart and blood vessels, kidney, and external covering around the organs; function: it's thin so it allows for easy diffusion and filtration. Also reduces friction.
Simple Cuboidal Single layer of cube shaped cells, usually with spherical nuclei. Covers ovaries and lines most of the kidney tubules and the ducts of certain glands. Major function:
Simple Columnar …
Psuedostratified Ciliated Columnar …
Stratified Squamous …
Glandular Epithelia one or more epithelial cells that makes and secretes an aqueous fluid- into a duct, onto a surface or into interstitial fluid
Exocrine …
Endocrine …
Connective Tissue …
Collagen fibers long, straight, and unbranched; most common fibers in connective tissue proper; flexible; tendons and ligaments, Composed of collagen: flexibility and strength
Reticular fibers fibroblast-like cells that produce the reticular fiber stroma,Composed of very thin collagen fibers
Highly branched: delicate support networks
Elastic fibers Flexible and "stretchy" fibers that add elasticity to tissue
Loose Fibrous Connective Tissue Has space between components
Supports epithelium and many internal organs (bladder)
Forms protective coating around many organs (muscles, blood vessels, nerves)
Dense Fibrous Connective Tissue Collagen fibers packed closely together
More specific functions than loose: Major function is
1-Tendons: connect muscle to bond
2-Ligaments: connect bones to other bones
Dermis layer of skin
Adipose Fibrous Connective Tissue Major functions:
Fat storage (primary energy reserve)
Locations of adipocytes:
Beneath skin
Around kidneys
Surface of heart
Number of adipose cells is fixed
Supportive Connective Tissue: Cartilage No direct blood supply (heals slowly)
Cells lie in small chambers called lacunae, which are separated by a matrix
Hyaline-Very fine collagen fibers, example:Nose; fetal skeleton; airway
Elastic-More elastic fibers = more flexible, example:Outer ear
Fibrocartilage-Strong collagen fibers, example: Between vertebrae and knee joint
Compact Bone (2 types) Osteons— cylindrical structural units
Central canal surrounded by hard matrix
-located in lacunae
Blood vessels in central canal
Fluid Connective Tissue: Blood Consists of numerous cell types and matrix
Matrix = plasma = liquid portion of blood
Each cell type has specific function
Hematopoiesis = production of blood cells
Major functions:
Carry oxygen and nutrients to tissues
Remove CO2 and other wastes from tissues
Erythrocytes: Red Blood Cells Small, biconcave, disk-shaped cells
Lack a nucleus!
Contain hemoglobin
Composed of protein components and a heme group (contains iron)
Transports oxygen through the body
Leukocytes: White Blood Cells Larger than red blood cells
Contain a nucleus
Major function: fighting infection
Some are phagocytic
Some produce antibodies
Lymph: fluid that carries white blood cells throughout body
Contained in lymphatic vessels that drain into lymph nodes
Muscular Tissue Tissue that contracts and moves various parts of the body,
AKA contractile tissue
Contain actin and myosin filaments
Important for generation of body heat
Three types:
Skeletal Voluntary muscles
Fibers are cylindrical and long
Cells contain multiple nuclei
Located at periphery of cell, just inside cell membrane
Striated due to placement of filaments
Smooth Muscles AKA involuntary
No striations
Spindle-shaped cells, each with one nucleus
Major function:
Movement of substances in lumens of body
Ex: blood in blood vessels, food through digestive system
Cardiac Muscles Found in heart
Combined features of skeletal and smooth:
Has striations (like skeletal)
Involuntary (like smooth)
Single nucleus (like smooth)
Intercalated disks: connect cells; adhesion and gap junctions
Nervous Tissue Major function: sensory input, data integration, motor output
Contains neurons: nerve cells
Neurons are specialized cells with 3 important components:
Dendrites: carry signals toward cell body
Cell body: contains nucleus
Axon: carries signals away from cell body
Covered in myelin sheath: fatty substance
Dendrites carry signals toward cell body
Cell body contains nucleus
Axon carries signals away from cell body
Covered in myelin sheath: fatty substance
Neuroglia Cells that support and nourish neurons
Part of the nervous system, but not neurons!
Three main cell types:
Microglia: immune cells; engulf bacteria and cell debris
Astrocytes: provide nutrients to neurons
Oligodendrocyte: form myelin
Most brain tumors actually involve these cells
From Tissues to Organs Four main types:
Organ: two or more types of tissues working together to perform specific function
Organ system: many organs cooperating to carry out a process (such as food digestion)
Organ Systems memorize this chart on slide 38
Body Cavities Two main body cavities:
Dorsal—is the back cavity
Homeostasis maintenance of normal internal conditions in cell/organism via means of self-regulating mechanisms
Organ systems are important for homeostasis
Respiratory system: takes in oxygen, removes CO2
Liver/pancreas: blood sugar levels
Controlled by hormones; ultimately: nervous system
Regulation of Homeostasis Two types:
Negative (most common)
Two main components:
Sensor: detects a change in internal environment
Control center: cause effects to bring conditions back to normal
Set point: normal conditions
Types of Blood Vessels Chapter 32-34 Arteries: carry blood away from the heart
Capillaries: exchange materials with tissue fluid
Veins: return blood to the heart
Blood Vessel Structures Arteries and veins: 3 distinct layers
Outermost: fibrous connective tissue
Middle: Smooth muscle and elastic tissue
Innermost: endothelium (similar to squamous epithelium)
Capillaries: endothelium layer only
One cell thick
Capillaries Extremely narrow
Blood cells: single-file
Arteries Thick walls
Resilient: expand to accommodate blood flow from heart
Veins Thinner walls
Contain valves to prevent backflow of blood
Double-loop Circulatory Pathway Two loops/circuits:
Pulmonary circuit
Heart pumps blood to the lungs (to drop off CO2 and pick up oxygen)
Systemic circuit
Heart pumps blood to tissues (to deliver oxygen and pick up CO2)
Heart Anatomy Heart = myocardium
Cone-shaped, muscular organ
Contained in pericardium: thick membrane that surrounds the heart
Inner surface: lined with endocardium
Membrane composed of connective tissue and endothelial tissue
Endocardium is continuous with endothelium in blood vessels
Atrioventricular valves …
Semilunar valves …
bicuspid …
tricuspid …
Internal Heart Anatomy slide 11 must know chp 32
Flow of Blood Through the Heart [part1] Remember:
Veins carry blood into the heart
Arteries carry blood away from the heart
Oxygen-poor blood comes from tissues to heart
Comes via superior and inferior vena cavae
Arrives into right atrium
Passes through atrioventricular valve (tricuspid)
Enters right ventricle
Hint: you NEED to know this information for the exam
Flow of Blood, continued [part2] From R ventricle, blood passes through semilunar valve to enter pulmonary arteries
Artery = away from heart; pulmonary = to lungs
Blood goes to lungs: comes back to heart oxygen-rich
Oxygen-rich blood enters through pulmonary veins
Veins = into heart; pulmonary = from lungs
Flow of Blood, continued [part3] Blood enters left atrium
Passes through atrioventricular valve (bicuspid)
Enters left ventricle
Passes through aortic semilunar valve to the aorta
Main artery that carries oxygen-rich blood away from the heart and into the body
Vascular Pathways Two main circuits:
Pulmonary: blood flow to/from lungs
Systemic: blood flow to/from everywhere else
Oxygen-poor blood enters heart through vena cavae
Right atrium - tricuspid - right ventricle - semilunar
Pulmonary trunk: divides into pulmonary arteries
Systemic Circuit Major blood vessels:
Vena cavae (veins: carry blood to heart)
Aorta (artery: carries blood away from heart)
Aorta branches to go to organs/major body regions
arteries - arterioles - capillaries - venules - veins
All veins eventually empty into either superior vena cava or inferior vena cava
Hepatic portal vein Carries blood from intestines to liver
Intestines: absorb nutrients
Liver: filter/modify blood
Rh factor Another antigen: Rh factor
85% of population has Rh factor (positive)
Rh- individuals: don't normally have anti-Rh antibodies but can develop them if exposed
Important during pregnancy!
If mother is negative and baby is positive: mother may produce anti-Rh antibodies
These antibodies can cross placenta: target baby's blood cells!
Babies require immediate blood transfusion to survive
Cardiovascular Diseases Hypertension: high blood pressure
Atherosclerosis: accumulation of soft masses of fatty materials
Plaques = fatty deposits in blood vessels
Interfere with blood flow
Path of Food Through the Digestive Track Mouth
Pharynx and Esophagus
Small Intestine
Large Intestine

Accessory organs: pancreas, liver, gallbladder
Digestion Details Digestion is extracellular
Two major stages:
Mechanical digestion: physical breakdown into smaller pieces
Chewing; physical churning/mixing in stomach and small intestine
Chemical digestion: enzymatic breakdown
Specific enzymes break macromolecules into smaller molecules
Mouth First stages of digestion:
Mechanical: chewing
Chemical: amylase
Tongue: striated muscle tissue surrounded by mucous membrane
Food formed into bolus
Mass that is swallowed
bolus A term used to describe food after it has been chewed and mixed with saliva
Esophagus tube that carries bolus to stomach
Lower gastroesophageal sphincter: "valve" at the bottom of the esophagus
Must open to allow food in
Structure to right found in:
Intestine (small and large)
a muscular tube that connects the mouth to the stomach
Peristalsis Rhythmic contraction that moves contents through tubular organs
Stomach J-shaped organ
Capacity: ~ 1 liter
Gastric pits secrete gastric acid (HCl) and pepsin
Stomach pH = 2
Stomach protected by mucus
Food + gastric juices = chyme
Small Intestine the longest part of the digestion system,Narrow, long (6 meters!) tube
Major functions: complete digestion and absorb nutrients
In duodenum (first 25 cm): chyme mixes with bile (from liver/gallbladder)
Bile emulsifies fat
Large surface area (tennis court)
Sugars, amino acids: enter bloodstream
Fats: enter lymph (lacteal)
pepsin Enzyme that breaks down proteins in the stomach, An enzyme present in gastric juice that begins the hydrolysis of proteins.
amylase enzyme in saliva that breaks the chemical bonds in starches
chyme Mixture of stomach fluids and food produced in the stomach by contracting stomach muscles
duodenum first part of small intestines, most digestion takes place, chemicals released from liver, gall bladder, and pancreas
Large Intestine Components:
Cecum (and appendix)
Larger in diameter, but shorter, than small intestine
Absorb water, salts, some vitamins
Waste storage
Home to a large population of bacteria
Aid in digestion
Produce vitamins (like Vitamin K, important for blood clotting)
Protect against pathogenic species
Accessory Organ: Pancreas Located in abdominal cavity
Both endocrine and exocrine function
Endocrine: secretes insulin and glucagon
Exocrine: secretes pancreatic juice (NaHCO3 and digestive enzymes)
Amylase: digests starch
Trypsin: digests protein
Lipase: digests fat
Accessory Organ: Liver Largest gland in the body
Secretes bile
"Gatekeeper to the blood"
Blood comes from intestines to liver via hepatic portal vein
Accessory Organ: Gallbladder Pear-shaped, muscular sac that is attached to the liver
Major function: storage for bile
When needed, bile leaves gallbladder and enters duodenum
Gallstones: crystallized cholesterol in bile
Stones can block the common bile duct
Trypsin enzyme that breaks down proteins
Lipase an enzyme secreted in the digestive tract that catalyzes the breakdown of fats into individual fatty acids that can be absorbed into the bloodstream
Carbohydrate Digestion starts in the mouth with amylase converting polysaccharides to disaccharides, continues with pancreatic amylase, finishes with sucrase/maltase/lactase from the small intestine converting disaccharides to monosaccharides (glucose/fructose/galactose)
Starch hydrolysis
Two varieties:
Maltose → Glucose
Small intestines
Enzymes and disaccharides
Protein Digestion Begins in the stomach, hydrochloric acid breaks down protein structure (denaturation) and activates pepsin. Pepsin is an enzyme that breaks down proteins into short polypeptides and amino acids
.Protein hydrolysis:
Pepsin: stomach
Trypsin: pancreas
Pepsin and trpysin: make peptides
Peptides→amino acids
Small intestine
Fat Digestion Step 1:
Fat emulsified by bile salts
Step 2: Lipase
Pancreatic enzyme
Breaks fats into glycerides and fatty acids
Packed into chylomicrons