Honors Biology - Unit 2: Cells

Unit 2 Exam: Thursday 11/06/25

structures present in eukaryotic and prokaryotic cells

• ribosomes

• cytoplasm

• DNA

• cell membrane

unicellular cell

prokaryotic cell

multicellular cell

eukaryotic cell

location of DNA in prokaryotes

nucleoid (cytoplasm)

location of DNA in eukaryotes

nucleus

prokaryotes have/don't have vs eukaryotes

• no nucleus

• no membrane bound organelles

• DNA in cytoplasm/nucleoid

eukaryotes have/don't have vs prokaryotes

• nucleus

• membrane bound organelles (GA, ERs, mitochondria, lysosomes, vacuoles, chloroplasts)

• DNA in nucleus

nucleus

stores genetic material (DNA) and controls cell's activities

nucleolus

in nucleus and where ribosomes are made

SER

creates/stores/transports lipids and carbs

RER

network of membranes studded with ribosomes that produces proteins

ribsome

where proteins are produced

golgi apparatus

modifies proteins and lipids and prepares it to leave cell

mitochondria

powerhouse of cell generating ATP

chloroplast

organelle in plant cell capturing light energy and converting it to chem. energy (photosynthesis

cell wall

outer layer in plant cell providing support and protection

cell membrane

flexible bilayer regulating what goes in/out

cytosol

jelly-like liquid portion of cytoplasm

cytoplasm

entire contents of cell including cytosol and organelles suspended within it

vesicle

small membrane-bound sacs transporting molecules within cell

plant vacuole

large permanent sac storing water and nutrients

lysosome

sac containing digestive enzymes that break down waste materials

organelles only in animal cells

lysosomes and small temporary vacuoles

organelles only in plant cells

chloroplasts and large permanent vacuole

organelles in both animal and plant cells

ERs, GA, mitochondrion

not organelles

cytoplasm/sol, cell membrane/wall, ribosomes, nucleus

levels of structural organization

cell, tissue, organ, system, organism

cell

smallest living unit existing, building blocks of life

tissue

made by cells similar in structure and function

organ

group of different tissues that work together

system

group of organs that work together to perform specific function for organism

organism

entire living thing carrying out basic functions, organ systems work together to maintain homeostasis

specialized cell

cell that performs a specific function due to cell differentiation

what makes 1 cell different from another cell, how do they specialize?

mature through cell differentiation, different genes are expressed, location in embryo

defining characteristics of stem cells

develop into different specialized cell types, can divide and renew

stem cell categories

totipotent, pluripotent, multipotent

totipotent

fertilized egg found in zygote that can give rise to any other cell including toti. to a certain point

pluripotent

embryonic stem cell that can give rise to any other cell but totipotent

multipotent

adult/somatic stem cell that can give rise to cells closely related to that cell type

stem cells vs specialized cells

stem cells: unspecialized, can divide, no function, vice versa

why should cells remain small?

to maintain high SA:V

2 aspects of cell size

surface area and volume

why is a cell with a larger surface area but small volume more efficient?

because it can absorb nutrients faster and get rid of waste faster

features that cells have to increase SA

microvilli

features that organs have to increase SA

folds, villi, microvilli

cell can travel/move from 1 location to another

mighty motors move

mitochondria (ATP), bundle of microtubules/flagellum

cell can take in and trap harmful substances

very sneaky little trappers

vesicles, cell membrane is fluid/can change shape, lysosomes

cells that allow for movement of a multicellular organism

muscles need energy

microfilaments, mitochondria (ATP)

sends and recieves signals throughout multicellular organism

very long communicators

vesicles, long shape with projections

cell can synthesize/package/store/modify/secrete hormones

really great shipping

vesicles, ribsomes, golgi

cell can absorb large quantities of nutrients quickly

microvilli

neuron

sends and recieves signals

pancreatic

stores and secretes insulin

muscle

specialized for movement

intestinal

absorbs nutrients from intesting

macrophage

fights infection from microbes (bacteria)

sperm

swims to and fertilizes egg

4 main stages of cell cycle

gap 1, synthesis, gap 2, mitosis

G1

cell grows larger and produces what it needs to synthesize (DNA)

S

cell replicates its DNA

G2

cell grows larger and makes more proteins/structures as cell prepares for mitosis

M

cell duplicates all contents including chromosomes

when is cell cycle regulated?

at checkpoints in each stage (G1, S, G2, M)

importance of checkpoints

to ensure cell divides correctly, only when ready

what can go wrong if cell cycle isn't regulated?

uncontrolled cell division, cells divide without order and accumulate genetical errors = tumors = cancer

purpose of M phase of cell cycle, why do cells need to divide?

growth and repair

4 phases of mitosis

PMAT: prophase, metaphase, anaphase, telophase

prophase

chromatin condenses into identical chromosomes

metaphase

chromosomes line up in middle of cell

anaphase

sister chromatids pulled apart to poles

telophase

arrive at poles, start to see 2 nucleii again

what kind of cells produced during mitosis?

2 identical daughter cells with same DNA

what occurs during cytokinesis?

cytoplasm of parent cell divides to form 2 seperate cells

cytokinesis in animal cell

cleavage furrow forms on cell's surface (ring made of actin/myosin contract)

cytokinesis in plant cell

cell plate forms in center of cell (formed by vesicles' fusion to form cell plate)

regulatory checkpoints

control points in cell cycle that monitor and ensure proper cell division, preventing duplication of damaged replicated material

cell at rest

G0 phase, where cell continues to perform normal functions without preparing for division

what happens if there are mutations in process that control checkpoints?

cancer (eventually), because cell's ability to pause and repair errors before dividing is lost-- allows cell to replicate unready DNA

2 factors of cancer

oncogenes (mutated proto-oncogenes) and mutations in tumor suppressor genes stimulate cell division even more

features of cancerous cell vs normal cell

uncontrolled growth -> invasion of healthy cells

rate of division in cancerous vs healthy cell

higher rate of cell division in cancer cell