TEAs science (biology mostly)

squeak no anatomy/chemistry included :P

cells

the basic unit of life

tissue

made up of cells with similar structure and function

organs

made up of tissue that work together to function

organ systems

groups of organs that work together to carry out a function

organism

made up from one or more organ system

biological organization

1. cells

2. tissues

3. organs

4. organ systems

5. organisms

modern cell theory

1. the cells are the smallest living unit in all organisms

2. all living things are made up of cells

3. all cells come from other pre-existing cells

prokaryotes (PRO = NO)

examples: bacteria + archaea

characteristics →

1. DNA

2. Cytoplasm

3. Ribosomes

4. Cell membrane

5. NO NUCLEUS

6. NO MEMBRANE BOUND ORGNELLES

   1. ex: nucleus + mitochondria + golgi apparatus

Eukaryotes (EU = DO)

examples: fungi + protist + plants + animals

characteristics →

1. DNA

2. Cytoplasm

3. Ribosomes

4. Cell membrane

5. NUCLEUS

6. HAS MEMBRANE BOUND ORGANELLES

cell membrane (plasma membrane)

separates the inside of the cell from the outside environment

characteristics →

1. selectively permeable

   1. only specific materials can come in and out

2. keeps cells stable (HOMEOSTASIS)

homeostasis

self-regulating process by which biological systems maintain stability while adjusting to changing external environment

cytoplasm

gelatinous liquid that fills the inside of a cell :3

cytoskeleton

network of fibers that provide structural support for the cells and organelles

• helps with cellular movement

ribosomes

intercellular structures made of both RNA and protein

1. site of protein synthesis in the cell

2. can either float freely or is attached to another organelle

other words: is primarily responsible for assembling proteins using instructions encoded in mRNA

amino acids

small molecules that are the building blocks of proteins

nucleus

membrane-enclosed organelle within a cell that CONTAINS the chromosomes (DNA)

→ ONLY FOUND IN EUKARYOTES

nucleolus

area inside the nucleus of a cell that is made up of RNA and proteins and is where RIBOSOMES are made

endoplasmic reticulum

large structure that serves many roles in the cell including

1. calcium storage

2. protein + lipid synthesis

3. lipid metabolism

comes in 2 forms… ROUGH ENDOPLASMIC RETICULUM and SMOOTH ENDOPLASMIC RETICULUM

rough endoplasmic reticulum

provides surface area for chemical reactions + protein synthesis/transport

• rough appearance due to the surface being covered in ribosomes

smooth endoplasmic reticulum

1. makes cellular products like hormones and lipids

2. detoxification, a vital process for liver cells

• smooth appearance due to the lack of ribosomes

golgi apparatus (UPS/USPS)

helps process and package proteins and lipid molecules, especially PROTEINS destined to be exported from the cell

ENZYME ASSISTANCE:

receives materials from transport vesicles that detach from the ROUGH ENDOPLASMIC R

→ enzymes modify molecules and organize them

mitochondria (POWERHOUSE of the cell)

generates most of the chemical energy needed to power the cell’s biochemical reactions.

→ generates on GLUCOSE

other words: generates ATP energy through cellular respiration

Adenosine Triphosphate (ATP)

source of energy for use and storage at the cellular level

chloroplast

plant cell

→ saclike organelle with a double membrane that services as a site for photosynthesis

• gets its green appearance from the pigment they absorb from light energy

photosynthesis

energy from the sun that’s converted into chemical energy for growth

lysosomes

the cells waste disposal system

→ contain digestive enzymes that break down excess/worn-out cells + macros

• may be used to DESTROY VIRUSES + BACTERIA

Maintain cellular cleanliness + recycle materials that can be reused by the cell

vacuole

large fluid-filled sacks found in (MOSTLY) plant cells and some animal/fungal cells

functions →

1. storing nutrients

2. maintaining hydrostatic pressure within the cell (plant)

3. help sequester (isolate) waste/harmful products (animal)

Mitosis

cell division that results in TWO daughter cells; each having the SAME NUMBER and kind of chromosomes

differences from meiosis:

1. leads to SOMATIC CELLS (body cells)

Meiosis

cell division that results in FOUR daughter cells each with HALF THE NUMBER of chromosomes of the parent cell

differences from mitosis:

1. produces REPRODUCTIVE CELLS, known as gametes (sperm/eggs)

2. included the stages TWICE (prophase 1/2, metaphase 1/2, anaphase 1/2, and telophase 1/2)

2n

both mitosis + meiosis start off as a DIPLOID CELL (2n) , which simply means two complete set of chromosomes

how many chromosomes do we have?

46 chromosomes

• 23 from our mom

• 23 from our dad

Interphase

cells replicate their chromosomes

→ still referred to as 46 chromosomes because they are simply copies known as CHROMATIDS that remain joined at the region called the CENTROMERE doubling the chromatid number to 92

• technically not a part of the mitosis/meiosis process, but is crucial for chromosome replication and sets the stage for what’s to come

mitosis (PROPHASE)

initial stage when it comes to division (pro = before)

→ chromosomes become visible as they condense + thicken

meiosis (PROPHASE 1)

→ chromosome condensation occurs and will also begin pairing up in HOMOLOGOUS CHROMOSOMES

• allows for the exchange of genetic material between chromosomes through CROSSING OVER, which results in RECUMBENT chromosomes important for genetic diversity

homologous chromosomes

equal in size/gene type/location

• one came from the mother and the other from the father

mitosis (METAPHASE) (think MIDDLE)

ps: the nuclear envelope that was previously enclosed in the nucleus has been dismantled (pulled apart)

→ chromosomes align in the middle of the cell’s center; forming a single row

meiosis (METAPHASE 1)

→ chromosomes align in the middle of the cell’s center, BUT maintain their homologous pairs, creating a pair of chromosomes standing together in the middle (NOT A SINGLE ROW)

mitosis (ANAPHASE) (think = AWAY)

→ CHROMATIDS are separated and drawn to the opposite ends of the cell by spindle fibers

REMEMBER NOT CHROMOSOMES

meiosis (ANAPHASE 1)

→ CHROMOSOMES are separated and drawn to the opposite ends of the cells by spindle fibers

• homologous chromosomes are separated as it allows for the random assortment of chromosomes, contributing to GENETIC DIVERSITY among offspring

REMEMBER NOT CHROMATIDS THAT ARE FOR MITOSIS

mitosis (TELOPHASE)

→ chromosomes reach the opposite sides of the cell; forming new nuclear envelopes around the chromosomes and setting the stage for the CREATION OF TWO BRAND NEW CELLS

*mitosis

meiosis (TELOPHASE 1)

→ chromosomes reach the opposite sides of the cell, forming new nuclear envelopes around the chromosomes and setting the stage for the CREATION OF TWO BRAND NEW CELLS

*meiosis

mitosis (CYTOKINESIS)

→ the division/splitting of the cytoplasm and is going to FINALIZE the cell division process

• results: two identical, diploid cells (both have 46 chromosomes)

meiosis (CYTOKINESIS)

→ the splitting of the cytoplasm of the cell

meiosis (PROPHASE 2)

→ chromosome condensation in both cells

• less eventful compared to prophase 1 as there are no more homologous pairs

meiosis (METAPHASE 2) (think MIDDLE)

→ chromosomes align in the middle of the cell’s center, forming a single row

• similar to mitosis metaphase

meiosis (ANAPHASE 2) (think AWAY)

→ CHROMATIDS are separated and drawn to the opposite ends of the cells by spindle fibers

• in anaphase 1 they were still chromosomes, however, it is important to remember that they are not chromatids :3

meiosis (TELOPHASE 2)

→ chromosomes reach the opposite sides of the cell, forming new nuclear envelopes around the chromosomes leading to the creation of new cells

meiosis (CYTOKINESIS) again..

→ splitting of the cytoplasm again

• results: four non-identical (DISTINCTIVE) cells/gametes

men: sperm

women: eggs

→ both are haploid cells carrying half of the chromosome count of the original cell (23 chromosomes)

other info: the fusion of sperm and an egg creates a diploid cell (fertilized egg known as a zygote)

summary of mitosis vs meiosis

mitosis results in TWO genetically identical diploid daughter cells

meiosis produces FOUR genetically unique haploid cells

heredity

the passing on of physical or mental characteristics genetically from one generation to another

• examples: height, hair color, eye color, risk of certain diseases, etc.

→ DNA is responsible for coding the traits that define us

DNA (deoxyribonucleic acid)

self-replicating material that is present in NEARLY all living organisms as the main constituent of chromosomes

→ fall into the category of nucleic acids

feature 3 critical components

1. Deoxyribose (a sugar)

2. a Phosphate group (known as the sugar-phosphate backbone of DNA)

3. nitrogenous base

• has 4 types of bases (A, T, C, and G)

  1. Adenine

  2. Thymine

  3. Cytosine

  4. Guanine

nucleic acid

one of our essential biomolecules is composed of building blocks known as nucleotides

Pairing of nucleotide bases

1. Adenine and Thymine

   1. REMEMBER → APPLE in the TREE

2. Cytosine and Guanine

   1. REMEMBER → CAR in the GARAGE

DNA structure

consists of TWO strands with nucleotides aligned along each side of them

→ in the center the bases of opposite stands are going to pair up, connected by HYDROGEN BONDS

• structure of DNA will twist into a DOUBLE HELIX SHAPE

REMEMBER: nucleotides

nucleotide bases are held together with HYDROGEN BONDS

genes

segments of DNA create genes

→ a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristics of the offspring

structural genes

specific regions of DNA correspond to individual genes capable of encoding proteins

→ CRUCIAL TO TRAIT EXPRESSION

• ex: human eye color/hair color

other functions:

1. transport

2. structure support

3. enzymatic activity (facilitates synthesis for several substances)

4. defense mechanisms

regulatory genes

non-coding regions 😽

→ produce proteins or RNAs that control the expression of other genes

• Gene regulation: used to control timing, location, and amount in which genes are expressed

genes can be activated and deactivated through various mechanisms

IMPORTANT (genes)

despite all of our body cells containing a complete DNA code only specific gene segments may be used with certain genes being activated and others being deactivated (gene regulation)

gene regulation

used to control the timing, location, and amount in which genes are expressed

chromosomes

DNA is compacted/organized into these structures

→ a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes

• consists of DNA coiled around a protein scaffold

• humans consist of 46 chromosomes

  • 23 from mom / 23 from dad

relationship between DNA, genes, and chromosomes

Chromosomes are composed of DNA, and genes are specific segments of chromosomes that dictate individual traits

• REMEMBER →

  1. chromosomes are long strands of DNA wrapped around proteins called histones

  2. Genes are located ON these chromosomes and act as instructions to produce proteins that determine characteristics

what best describes the function of regulatory genes in gene expression

they produce proteins or RNAs that control the expression of other genes

→ REMEMBER

1. regulatory genes are responsible for producing proteins and RNAs + play a crucial role in controlling expressions (enhance/inhibit gene expression)

RNA (ribonucleic acid)

→ a nucleic acid present in ALL living cells whose principal role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins

in eukaryotes, RNA is located INSIDE and OUTSIDE of the nucleus

RNA structure

is SINGLE-SIDED + has one single strand of nucleotides

• there is an absence of oxygen molecules

• there is a different sugar base (RIBOSE)

contains the nitrogenous bases of...

1. Adenine

2. Uracil (replaces thymine from DNA)

3. Cytosine

4. Guanine

pairing of nucleotide bases

1. ADENINE + URACIL

   1. APPLE UNDER the tree

2. CYTOSINE + GUANINE (same)

   1. CAR in the GARAGE

the 3 different types of RNA

1. mRNA

2. rRNA

3. tRNA

mRNA (messenger)

carries genetic information to make proteins

→ can exit the nucleus and allow it to transport the genetic blueprint to the RIBOSOMES to produce proteins

• composed of an RNA sequence that MIRRORS the DNA template + goes under ALOT of editing before working

rRNA (ribosomal)

found in ribosomes + serve as a location for protein synthesis

tRNA (transfer)

the primary function is to take amino acids to the ribosome + ensure that they align correctly with the corresponding mRNA codons to create a POLYPEPTIDE CHAIN

other words: an adaptor molecule that decodes an mRNA into a protein

protein synthesis unfolds through…

2 principal phases

1. transcription

2. translation

independent variable

VARIABLE THAT IS CHANGED

example → the amount of water poured on plants

dependent variable

variable affected by the change

example → the size of the plant, the number of leaves, or whether the plant is dead/alive

extra info: RNA

while DNA hold the instructions for traits it cannot be expressed with RNA

remember → RNA translates DNA’s genetic code into proteins

transCription (think = C comes before L)

involves converting DNA into a messenger strand; this takes place in the nucleus where DNA is found.

→ RNA polymerase (an enzyme) attaches matching RNA bases to the DNA templates to create a single-stranded molecule of mRNA

transLation (remember C comes before L)

where ribosomes assemble the proteins

in other words→ the process of translating the sequence of a mRNA to amino acids during protein synthesis

• in the cytoplasm, you’ll find multiple tRNA molecules that are responsible for carrying amino acids (protein’s building blocks)

• the mRNA will serve as a guide that determines which tRNA needs to be brought to a ribosome + which amino acid needs to be assembled to form a protein

• each tRNA will search for bases that match its mRNA strand.

• After finding matching bases the tRNA contributes its amino acids to the growing protein chain

result → a creation of an amino acid chain, assembled in a specific sequence that is dictated by the mRNA

codons

a sequence of THREE consecutive nucleotides in a DNA or RNA molecule that codes for a specific amino acid

what component is essential for initiating the transcription of a gene into mRNA in eukaryotic cells?

RNA polymerase

• reads the DNA sequence of a gene and creates a complimentary mRNA strand

what is the role of mRNA in protein synthesis?

it serves as a template for assembling amino acids into proteins

• mRNA = MESSENGER as it carries genetic code from DNA during transcription to the ribosome

allele

a variant of a gene often recognized by letters

in other words → an alternative form of a gene that arises by mutation and are FOUND IN THE SAME PLACE ON A CHROMOSOME

recessive allele

trait not expressed if there is a dominant allele

→ expressed as a LOWERCASE LETTER

dominant allele

trait will be expressed due to its dominance

→ expressed as a UPPERCASE LETTER

genotype

refers to the two alleles present at a specific locus in the genome + refers to the ENTIRE GENETIC MAKEUP of an individual

the two types of genotypes

1. homozygous genotype

   1. homozygous DOMINANT (FF)

   2. homozygous RECESSIVE (ff)

2. heterozygous genotype

   1. heterozygous DOMINANT (Ff)

monohybrid cross

genetic mix between two individual genotypes which result in an opposite phenotype for a certain trait

→ mono signifies that we are focusing on a SINGLE TRAIT

phenotype (think p → physical)

an individual’s OBSERVABLE TRAITS produced by the interaction of the genotype

examples → height, eye color, and blood type

extra info on punnet squares

they offer predictions BASED on PROBABILITIES not certainties!!

they do not guarantee anything :0)

dihybrid cross

cross between two individuals for two observed traits that are controlled by two distinct genes (two different alleles)

mendel’s law of independent assortment

suggests that traits are inherited independently of one another

→ there is NO genetic link between X and Y

example: just because someone has black hair it doesn’t mean they like to BLANK

incomplete dominance

one allele is not completely dominance over the other

codominance (co = working together)

both traits show up in codominance

→ both alleles are expressed equally in the phenotype + independently

Basic macromolecules

1. carbohydrates

2. lipids

3. proteins

and nucleic acids ( i guess.)

monomer

basically a building block (a smaller unit)

elements in the carbs

think CHO

1. carbon

2. hydrogen

3. oxygen

elements in lipids

think CHO

1. carbon

2. hydrogen

3. oxygen

*lipids

elements in proteins

think CHON

1. carbon

2. hydrogen

3. oxygen

4. nitrogen

elements in nucleic acids

think CHONP

1. carbon

2. hydrogen

3. oxygen

4. nitrogen

5. phosphorus

carbohydrates

biomolecule consisting of carbon, hydrogen, and oxygen atoms

THINK → cellulose, starch, and sugars

• monomer: MONOSACCHARIDE (simple sugar) like glucose

disaccharide (di → two)

when TWO monosaccharides link together

carbohydrate rule!!!

if the word ends in -OSE it most likely indicates a carb

examples:

1. glucOSE

2. fructOSE

3. maltOSE

4. sucrOSE

5. lactOSE