Biology Test: Cancer

Work Cited Zhang, Michael. ““A Month and a Half Til’ No Bio” (Meiosis, Disease & Viruses Test).” Google Docs, Bergen County Academies, 10 May 2026, docs.google.com/document/d/1PJauKA8Ki5RPk6Z8DPdx5y8lV8eN6n3dbXKdamvMqT0/edit?tab=t.4h5k67shgyed. Accessed 10 May 2026.

Cancer

A disease caused by an uncontrolled division of abnormal cells in a part of the body

Tumor

Swelling in the body as a result of an abnormal growth of tissue

Benign Tumor

Uncancerous cell growth, stays at the original site

Malignant Tumor

Cancerous cells that grow uncontrollably, spreading from the original site

Metastasis

The development of secondary malignant growths at a distance from a primary site of cancer.

Angiogenesis

The development of new blood vessels

Tumor Suppressor Genes

Genes which prevent cancer by controlling the cell cycle through inhibition.

Proto-oncogenes

Genes that code for proteins that stimulate normal cell growth and division

Oncogenes

Proto-oncogenes which are permanently activated, causing cancer by excessively stimulating the cell cycle.

Division: Normal vs. Cancerous

Cancerous cells are always stimulated, and thus continue dividing at an incredibly fast rate compared to normal cells

Size/Shape: Normal vs. Cancerous

Cancerous cells vary from each other, while normal cells are all ordered and similar

Nucleus: Normal vs. Cancerous

Cancerous cells have larger and darker nuclei than normal cells

Chromosomes: Normal vs. Cancerous

Cancerous cells have an abnormal number of chromosomes, not arranged in any particular way

Arrangement: Normal vs. Cancerous

Cancerous cells cluster together without boundary, while normal cells use contact inhibition

Contact inhibition

Cells stopping growth once touching another cell, stops excessive growth

Function: Normal vs. Cancerous

Cancerous cells either cannot carry out their function properly or lose the ability to completely

Repair: Normal vs. Cancerous

Cancerous cells do not undergo any repair or apoptosis when damaged

Apoptosis

Cell death, used to manage cells damaged beyond repair

Why do cancer cells induce angiogenesis?

Cancerous tumors require great amounts of nutrients, so they grow more blood cells to receive what they need

Mitosis use

Growth and repair

How does cancer develop?

Uncontrolled division, resulting from mutations permanently enabling stimulatory parts of the cell cycle or disabling inhibiting parts of the cell cycle

Oncogene mutations

Dominant

Tumor suppressor gene mutations

Recessive

Carcinogens

Substances that increase mutation rate or are toxic to cells, causing the development of cancer

Senescence

A cell that has passed the hayflick limit and can no longer divide (aging)

Causes of senescence

Telomere shortening (main one), DNA damage, oxidative stress, oncogene activation

Telomeres

Telomeres at the end of chromosomes get shorter and shorter after each division, with the cell entering senescence when it doesn't have enough telomeres to keep dividing

Telomerase

An enzyme in stem and cancerous cells that repairs telomeres, preventing it from reaching senescence

Oxidative Stress

Presence of free radicals and/or reactive oxygen species which damage DNA

Free radicals

Substances with unpaired electrons

Cell Cycle

Stages that cells go through as they grow and divide

Interphase

The phase of the cell cycle where it is preparing for division

G1

Cell grows in size

G0

A resting stage of the cell cycle in which DNA replication and cell division stop, can be entered from G1

Checkpoint at the end of G1

Checks for adequate cell growth, nutrients, and any DNA damage

S

Chromosomes divide

G2

Cell continues to grow

Checkpoint at the end of G2

Checks for the correct amount of chromosomes and any DNA damage

M

Mitosis, the phase where the cell divides

Prophase

Nuclear envelope breaks down, exposing the DNA to the cell, as the centrioles go to either side of the cell and the spindle forms

Metaphase

Chromosomes line up in the middle of the cell as the spindle attaches to their centromere

Checkpoint at the end of metaphase

Checks for spindle being attached to chromosome

Anaphase

Spindle drags chromosomes to either side of the cell

Telophase

Chromosomes become chromatin, as two nuclear envelopes form and cytokinesis occurs

Cytokinesis

Cell pinched in two to become two distinct daughter cells

CDKs

Cyclin-dependent kinases, proteins that phosphorylate others to make them carry out functions

Cyclin

Proteins which activate CDKs by binding and forming CDK complexes

Phosphorylation

The adding of a phosphate group to a molecule

Hayflick Limit

The maximum amount of divisions a cell can have, being ~50, a limit put in place by telomeres

Cancer in Tasmanian Devils

Have a unique contagious cancer known as Devil Facial Tumor Disease. Usually spreads through bites during mating or fights from cancer cells in oral cavities

Cancer in Sealions

Common urogenital cancer. Not contagious, but the sexually transmitted herpesvirus increases risk. Pollution also increases risk

Cancer in Elephants

They should have high rates of cancer, since they have so many cells dividing at the same time, with each division being a chance to develop cancer. However, they have 20 copies of p53, making cells undergo apoptosis and prevent cancer whenever stressors are present

Cancer in Naked Mole Rats

Have low rates of cancer because of p16, a protein that causes contact inhibition earlier

Cancer in Axolotls

Not elaborated on properly in class, but they basically just have really strong immune systems and anti-cancerous mucus (i doubt this info will matter much but js in case)

Topoisomerase

An enzyme which cuts and unwinds DNA, preventing tangling

Helicase

An enzyme which splits the two strands of dsDNA into single stranded DNA

RNA Primase

An enzyme which can assemble RNA primers, short segments of RNA

RNA Primer

Short segments of complementary RNA attached to DNA, 7-12 nucleotides long

DNA Polymerase

An enzyme which assembles dsDNA from ssDNA (by adding nucleotides) that can only form DNA in the 5' - 3' direction, building off of the 3' - 5' template

DNA Ligase

An enzyme which serves as "DNA glue", attaches gaps in the DNA backbone

Single Strand Binding Proteins

Proteins which stabilize ssDNA during replication.

Leading Strand

The strand which is synthesized from 5' - 3'

Lagging Strand

The strand which is synthesized from 3' - 5', uses Okazaki fragments

Okazaki Fragment

Short, discontinuous fragments of DNA, 100-200 nucleotides long

Exonuclease

An enzyme which removes RNA primers from synthesized DNA

Replication Fork

A Y-shaped region where the two strands were separated by helicase

Template DNA

Stand of original DNA that is replicated

p53

The guardian of the genome! It is a tumor suppressor gene that prevents the continuation of the cell cycle if it detects DNA damage

Activation of p53

Phosphorylated by kinases

MDM2

Controls p53 by promoting the ubiquitination of it, or degradation. Since MDM2 controls p53, and increased p53 causes increased MDM2, it displays a negative feedback loop.

Stem cells

Undifferentiated cells that can form other cells with specialization

Differentiation

The process through which a cell undergoes a change in size, shape, and function in order to be capable of carrying out a certain task and becoming specialized

Totipotent stem cells

Can differentiate into any cell in the body

Totipotent cells in humans

Fertilized egg cells

Pluripotent stem cells

Can differentiate into any cell other then placenta and extraembryonic tissue

Placenta tissue

Assists in pregnancy from within the uterus

Extraembryonic tissue

Forms things needed for pregnancy outside the uterus (Ex: Umbilical cord)

Multipotent stem cells

Can differentiate into cells relating to a certain tissue

Multipotent cells in humans

Found in small amounts in the organs (Ex: hematopoietic cells are found in bone marrow and form red blood cells, white blood cells, and platelets, but cannot form anything else anywhere else in the body, like nerves, muscles, etc.)

Unipotent stem cells

Can only differentiate into one type of cell

Unipotent cells in humans

Found in all tissue and organs (Ex: Muscle satellite cells repairing muscle tissue)

Meiosis Interphase

Same as mitosis interphase

Prophase I

Chromosomes condense, form a tetrad, and cross over as the nuclear envelope breaks down and the spindle begins to form

Tetrad

Sister chromatids attaching at the centromere in two chromosomes

Crossing Over

Homologous chromosomes swap parts of their chromatids with each other

Metaphase I

Tetrads line up at the metaphase plate and attach to centrioles

Independent Assortment

The order of tetrads in metaphase I is completely random

Anaphase I

The spindle separates the tetrads into the homologous chromosomes and brings them to opposite sides of the cell

Telophase I

Nuclear envelopes reform and cell pinches to form new cells

What does meiosis I end with?

Two haploid cells

Prophase II

DNA condenses and spindle reforms

Metaphase II

Chromosomes line up on the metaphase plate as centrioles attach

Anaphase II

Sister chromatids pulled to opposite sides of the cell by the spindle

Telophase II

Chromosomes recondense and nuclear envelopes reform, with the cell pinching it into two new ones

What does meiosis II end with?

4 haploid cells (all genetically different from each other)

Types of meiosis

Oogenesis and spermatogenesis

Spermatogenesis

Meiosis in males, forms four sperm cells

Oogenesis

Meiosis in females, produces one ovum and three polar bodies

Ovum

An egg cell

Polar bodies

Eliminate extra genetic information (prevents things like nondisjunction) and ensure that the ovum receives extra nutrients and cytoplasm