3.2

genetic material

substance that contains the information for how to build an organism and for what each cell should do = DNA

chromosome

one continuous DNA molecule (or two combined identical DNA molecules)

chromatin

DNA molecule wrapped around protein (histones)

• structure- organizes/compacts DNA

• function- regulated DNA

centromere

site (specific DNA sequence) where proteins bind to help divide chromosomes during cell division; creates a cinched waist

genome

the entirety of an organisms hereditary information

prokaryote has

singular circular chromosome

eukaryote has

multiple linear chromosomes

DNA replication

whole genome is duplicated so each daughter cell gets complete genome

sister chromatids

joined identical copies of original chromosome, created by DNA replication

mitosis

separation of sister chromatids and distribution to daughter cells (division of genetic material)

mitotic spindle

microtubules which pull the sister chromatids apart during mitosis; spindle extends from centrosomes

Kinetochore microtubules

• connect to proteins at centromere

• position chromosomes in center of cell and then pull apart

polar (nonkinetochore) microtubules

• overlap

• motors “push” rod-like MTs apart to elongate the cell

Prophase (1)

chromosome condense, spindle forms

Prometaphase (2)

nuclear envelope fragments; microtubules attach to chromosomes, each other

metaphase (3)

chromosomes line up

anaphase

sister chromatids separate, cell elongates

telophase

daughter nuclei form, chromosomes de-condense

cytokinesis

division of the cytoplasm at the end of mitosis

Interphase

G1- first gap

S- synthesis (dna replicated)

G2- second gap

Mitotic (M) phase

mitosis

cytokinesis

checkpoints

control point where stop and go signals can regulate the cell cycle

internal checkpoint: surveillance

ok to proceed?

dna damage?

chromosomes aligned properly?

external checkpoint: growth stimulus/inhibition

sufficient nutrients?

growth factor present?

enough space?

control molecules

• cyclin proteins

• cyclin-dependent kinases (CDKs)

• cyclin-CDK complex controls cell cycle progression

cyclin proteins

• level fluctuates (cycles)

• synthesis/degradation regulated by signals and negative feedback

cyclin-dependent kinases (CDKs)

• constant level

• activity depends on cyclins

cyclin-CDK complex controls cell cycle progression

ex: MPF (“mitosis promoting factor”)

S phase cyclin-CDK activates

DNA replication

cell cycle control genes

oncogenes and tumor suppressors

oncogenes

stimulate division

tumor suppressors

code for proteins that inhibit division or prevent cancer in other ways

stem cells divide to replace

themselves and give rise to new specialized cells

stem cell

unspecialized cell that produces new cells that can specialize

all blood cells are derived from

stem cells in bone marrow

embryotic stem cells

come from embryos and need to be able to make the whole body or any part of it (totipotent and pluripotent)

adult stem cell

found in specific parts of the body and only replace specific sets of cells in adults (unipotent, multipotent, or pluripotent)

ex: bone marrow → blood cells

normal body cells mostly divide

very rarely, and when told to

cancer cells divide

constantly and uncontrollably without any instruction

cancer cells take up

resources and space

causes of cancer

inherited mutations, spontaneous mutations, radiation, chemicals, viral oncogenes, immunodeficiency

BRCA1 and BRCA2 are

proteins that recognize damaged DNA and initiate DNA repair