Lecture A1, A2 Flashcards
Only universal characteristics of human cells
-eukaryotic
-animal cell (not plant cell)
Problem with textbook depictions of human cells
-has a collection of all the thing that can be in a cell but most cells don’t have all these characteristics
Histology is the study of ______
-cells on slides
Histology involves the ________
-preparation of tissue samples for study under a microscope
Histochemistry is the study of _____
cells using biochemistry/chemistry
Histochemistry involves the ______
the differential staining of cells based on chemical differences of the parts
Cell stains are useful because ______
tissues are mostly transparent (cells are mostly made of water)
Appearance of cells with cell stains are specific to ______
cell types
Cell biology is the study of ______
cells, their inner structures and their interactions with the environment in which they exist
Cell biology involves a number of scientific disciplines: ________ (4)
physics, biochemistry, physiology, and genetics
4 Characteristics of human cells
-diverse
-change over time/ develop
-morphology reflects function
-all have the same set of genes despite morphological differences
mass of average human cell
10^-12 - 10^-11
number of cells in human body
10^13 to 10^14
cells in human body are mostly ______
-red blood cells (84%), platelets (5%), bone marrow cells (2.5%)
humans are mostly ______
blood and stuff that make up blood (platelets, bone marrow lymphocytes etc.)
All human cells have the _____ but not all _______
-same genes
-genes are active in any given cell
humans are a bad lab animal because ______
-hard to breed
-lie (hard to measure)
-very diverse
humans are studied in the lab by ____
-taking human cells to study them
Most human cell studies are performed _____
on isolated cells grown in plastic dishes
HeLa cells characteristics
-can grow on plates
-more chromosomes in cell than regular 46
-transformed (cervical cancer cell)
stage where humans cells are all identical
8 cell stage (all similar without differentiation)
progression steps: zygote –> _____ –> ______ —-> ______
-morula
-blastula
-gastrula
morula (def.)
solid mass of blastomeres from multiple cleavages of zygote
blastula (def.)
hollow sphere of blastomeres with inner fluid filled cavity
blastula (descr.)
-has inner blastocoel (inner fluid cavity)
-has outer blastoderms (single layer embryonic epithelial tissue)
blastula grows and forms this next cell stage: ______
gastrula
gastrula is considered true human cells because the cells experience ______
cell differentiation
gastrula (def.)
early multicellular embryo, composed of 3 germinal layers of cells from which the various organs later derive.
gastrula 3 layers descriptions
-ectoderm (outer)
-mesoderm (middle)
-endoderm (inner)
blastopore is _______ (def.)
opening of the central cavity of gastrula
Gastrulation consists of ______
invagination of the blastomeres of one side of the blastula and cell differentiation leading to 3 layers
ectoderm forms ______ (3)
-outer surface (the skin cells of epidermis)
-central nervous system (neurons)
-neural crest (pigment cells - melanocytes)
mesoderm forms _____ (5)
-notochord
-skeletal muscle cells
-kidney cells
-red blood cells
-head (facial muscle)
endoderm forms ______ (3)
-digestive tube (ex. pancreatic cell)
-pharynx (ex. thyroid cell)
-respiratory cells (ex. lung cell)
What establish human cell diversity?
differences in gene expression
human cells are sorted into categories based on ______
their roles in the body
specialized cell for this activity: movement
muscle and other contractile cells
specialized cell for this activity: adhesive and tight junctions
epithelial cells
specialized cell for this activity: secrete parts of ECM
fibroblasts, cells of bone and cartilage
specialized cell for this activity: covert stimuli into action potentials
neurons and sensory cells
specialized cell for this activity: secrete degradative enzymes
digestive glands
specialized cell for this activity: secrete glycoproteins
mucous glands
specialized cell for this activity: secrete steroids
adrenal gland, testis and ovary
specialized cell for this activity: ion transport
kidney and salivary gland ducts
specialized cell for this activity: intracellular digestion
macrophages and neutrophils
specialized cell for this activity: lipid storage
fat cells
specialized cell for this activity: metabolite absorption
intestine cells
Cell differentiation depends on changes in _____ rather than on any changes in the _______
-gene expression
-nucleotide sequence of the cell’s genome
______ of a few key ______ drives cell differentiation.
-Combinatorial control
-gene regulatory proteins (transcription factors)
There are ______ genes in the human genome (approximately)
21306
Number of unique cell types in human cells
200 unique cell types
Type of proteins produced by the cell (5)
-transcription factors
-structural proteins
-enzymes
-signaling proteins
-organelle proteins
Differences in _____ provide cells with its unique properties and functions
protein expression
asymmetric division (def.)
sister cells are born different due to asymmetric inheritance of cellular components (e.g. proteins, RNAs) during mitosis
symmetric division (def.)
sister cells are born the same (equal inheritance) but become different as result of influence acting on them after their birth
Genes are encoded in ____
DNA which is in the nucleus
Eukaryotic DNA is packaged into _____
chromatin
euchromatin (def.)
transcriptionally active genes which are packaged less tightly
heterochromatin (def.)
repressed genes which are packaged more tightly
Types of transcription factors
1) activators
2) repressors
3) other TF
activator proteins do what?
bind to pieces of DNA called enhancers which causes the DNA to bend, bringing the gene promotor close to the proteins
other TFs + activator proteins = _____
protein complex that binds to gene promoter
the complex formed by activator proteins and other TF makes it ______
easier for RNA polymerase to attach to promoter and start transcribing
transcriptional memory means that ______
once a cell becomes a type of cell, it has to stay that type of cell
TFs are _____ (def.)
multi-protein complexes that are assembled on the DNA
TFs function (def.)
-can enhance or repress transcription from a gene
Function of TF changes depending on _____
the various proteins present
TF that you should know + (most -> least)
-ZNF-C2H2 – Zinc Finger (most)
-HLH - Helix-Loop-Helix (or Homeodomain (Homeobox))
-bZIP - Basic Leucine Zipper
-ZNF-GATA - Zinc finger protein that binds GATA (least)
Human TF genes are located where?
-in cluster within our chromosomes
TFs that bind to activate genes that specify hepatocyte (liver) cell (5)
-HNF1
-HNF3
-HNF4
-C/EBP
-AP1
HNF1 (def.)
hepatocyte-specific homeobox
HNF3 (def.)
hepatocyte-specific bHLH
HNF4 (def.) + expressed where?
-nuclear receptor that also is expressed in intestinal epithelial cells and kidney tubule cells
C/EBP (def.) + expressed where?
a bZip that also is expressed in intestinal epithelial cells, fat cells, and some neurons
AP1 (def.) + expressed where?
a small family of bZip proteins that are expressed in virtually all cell types
Potential (def.)
Cells with greater ‘potential’ can divide and differentiate
into a greater number of different types of cells
Specification (def.)
Cells have achieved a final fate
during development, human cells become more _____ and lose _____ in terms of their cell fate
-specific
-potential
Short term genetic memory of changes in gene transcription involves ______
TFs that regulate their own genes (increasing their production)
Short term genetic memory is lost during ______ because _____
-DNA replication (S-phase)
-TFs are removed as DNA is unwound and copied
Long term genetic memory is _____
epigenetics
Epigenetics involves ______ through _____ or ________
-heritable changes in chromatin that are not encoded in the DNA
-changes in chromatin structure by methylation
-by binding proteins to chromatin that block access to TFs and RNA polymerase
changes in chromatin structure regulate access to ______
coactivators/repressors and other TFs
Type of Histone Modifications
-methylation
-acetylation
-phosphorylation
Type of DNA Modifications (base level)
DNA base methylation (ex. cytosine)
DNA methylation is re-established by regulatory proteins ________ during the ______
-demethylases (remove)/ methyl transferase (add)
-cell cycle
long term epigenetic memory of gene activation/repression proteins are ______
maintained through the cell cycle
proteins that block access to TF and RNA polymerase II by binding to chromatin often recognize ____
methylated DNA bases
methylation of histone amino-terminal tail = _____
heterochromatin (condensed)
acetylation of histone amino-terminal tail = _____
euchromatin (relaxed)
number of TFs that create human cell diversity
510
Most TF in human body are _____ and some are _____
-tissue specific
-ubiquitous : expressed in different cell types
