Bio Semester 2 Final

Mitosis

Once the sperm fertizilies the egg, the egg (zygote) undergoes repeated cell division, this creates identical daughter cells

Zygote

The fertilized egg, result of sperm fertilizing an eggthat undergoes mitosis to develop into an embryo.

Egg to zygote

An egg is referred to a zygote when it begins to split

Differnentiation

A process that creates special structure and functions

Organization of an organism

Cells, tissues, organs, organ system, organism

Ectoderm

External layer (skin cells)

Mesoderm

Middle layer (skeletal)

Endoderm

Internal layer (lung cells)

Stem cell

Undifferentiated cell t5hat can differentiate into one or more types of cells

Purpose of cell cycle

Growth and repair of damaged tissues, replication of DNA, and cell division.

3 main cell cycle phases

Interphase (cell growth), mitosis (cell division), cytokinesis (cytoplasm splits)

Interphase stages

G1, S, G2

G1 (gap 1 phase)

Cell grow and makes proteins

S phase (synthesis)

DNA replication ossurs, doubling the numer of chromosomes or genetic material

G2 (gap 2 phase)

More cell growth and proteinsynthesis

Chromotid

One half of a duplicted chromosome

Centromere

The region of a chromosome where sister chromatids are joined and where the spindle fibers attach during cell division.

Telomere

Repetatve RNA sequence that protects teh chromosome

Sister chromotid (identical)

Two alike chromotids connected by the centromere

Homologous chromosomes

Code for the same genes, but are not identical, get one from mom and the other from dad

Prophase

Chromosmes condense, nuclear envelope breaks down, spindle fibers appear

Prometaphase

Spindle fibers attatch

Metaphase

Chromosome line up in the middle

Anaphase

Sister chromotids are pulled toward opposite poles

Telophase

Spindle breaks down, nuclear envelope reforms after chromosomes arrive at the poles

Proteins

Macromolecule that regultes the cell cycle

Chemical controlo system

The Cell Cycle is controlled by this and starts and stops events in the cycle

Cyclins

Regulator of the cell cycle

External regulation

Signals that come from outside the cell (hormones, nutrients, etc)

Internal regulations

Signals that come from the cells own nucleus (Like RNA code telling the cell what to do)

Checkpoints of cell cycle

Crtical points where “stop” and “go” signals can regulate the cycle

G2 checkpoint

Cell size and DNA replication

Metaphase checkpoint

spindle fibers attatched

G1 checkpoint

No DNA damage

G0

Resting state

Cancer

Uncontrolled cell divison, which happens when the regulation of the cell cycle doesn’t work properly for some reason

Turmos

Clumps of cells that divide uncontrollably

Benign tumors

Abnormal cells typically remain clustered together, may be harmless and easily removed

Malignant tumors

Cancer cells that break away from the tumor and more to other parts of the body, more tumors

Metastazise

Spread disease from one organ to another (Malignant tumors)

Causes of cancer

Biological factors, l8festyle choice, viruses and other infections, exposure to carcinogens (cancer-causing agents)

Apoptosis

Programmed cell death

Somatic cells

(Body cells) Diploid (2n), any normal cell

Gametes

(Sex cells) Haploid (n), only egg and sperm cells

Diploid cells

Two sets of chromosomes (2n)

Haploid cells

One full set of chromosomes (n), only one set that is a combo of genes from the gamete maker

Autosomes

Chromosomes that carry traits that make you who you arem first 22 pairs of chromosomes

Sex chromosomes

Carry rtriates that make you who you are AND determine your biological sex, ONLY the 223rd pair of chromosomes, known as X or Y (XX=female, XY=male)

Meiosis

The process of cell division that makes gametes in the gonads, produces haploid sex cells with HALF the number of chromosoems as diploid cells

Gonads

ovaries (females), or testes (males)

Meiosis 1

Homologous seperate, reducing the chromosomes number by half

Interphase (meiosis 1)

Diploid, a preparatory stage where the cell grows, replicates its DNA, and prepares for cell division

Prohase 1 (meiosis 1)

Chromosomes condense and pair up with their homolouge to forma homologous pair. Crossing over

Metaphase 1 (meiosis 1)

Homologous parts line up at the middle. Indepdendent assortment

Anaphase 1 (meiosis 1)

Homologous parts seperate

Telephase 1 (meiosis 1)

2 haploid daughter cells are formed (each chromosome is still attached to its copy)

Prophase 2 (meiosis 2)

Spindle fibers begin to capture chromosomes

Metaphase 2 (meiosis 2)

The chromosomes line up individually along the middle of the cell

Anaphase 2 (meiosis 2)

Sister chromotids seperate

Telophase 2 (meiosis 2)

Each cell is split in two, nuclear membrane form around each set of chromsomes

Crossing over

The chromosomes exchange parts of themselves

Independent assortment

Orrientation is random

Gene

Sections of DNA that provde instructions for making proteins

Allleles

Different versions of the same gene

Gregor Mendel

He was an Australian monk who used pea plants to learn about genetics. Father of Genetics

Laws of Inheritance

Law of Dominance, Law of Segregation, Law of Assortmant

Mendel’s experiments

Control over breeding, used only purebred plants, observed “either-or-traits”

Law of dominance

a dominant (strong allele) will express itself over a recessive (weak) allele

Dominant (allele)

Allel will always have that trait expressed (seen)

Recessive (allele)

Allele will only have that trait expressed when the dominant allele is NOT present

Genoytype

The actual allele inherited (AA, Aa, aa)

Phenotype

The physical characteristics or traits of organisms

Homozygous

2 of the same alleles (AA, aa)

Heterozygous

2 different alleles (Aa)

Law of segergation

When chromosome seperate in meiosis, each gamete (egg or sperm) will receive only one chromosome from each pair.

Law of independent assortment

The assortment of chromosomes for one trait doesn’t affect the assortment of chromosomes for another trait

Punnet squares

A diagram that shows the probability of inheriting traits

Dihybrid cross

Helps predict the probability of inheriting the conditons for two traits

Chromosome theory of inheritance

Genes are located on chromosomes and the behavior of chromosomes during the meiosis accounts for the inheritance patterns

Exceptions to Mendel’s laws

Incomplete dominance, codominance, multiple alleles, polygenic traits

Incomplete domiancne

Where the heterozygous phenotype is somewhere between the two homozygous phenotypes

Codominance

Both traits are fully and separately expressed

Blood type

An example of codominance and multiple alleles

Multiple alleles

Having more than two alleles for one gene

Polygenic inheritance

A trait produced by two or more genes, usually shows a range in phenotype

Linked genes

Genes that are physically located on the same chromsomes will be inherited together

Linked genes seperated

Can only be separated or broken apart during crossing over

X-linked genes

Genes on the X chromosomes are X linked

Female inherited genes

Inherit genes as normal and principles of dominance alleles

Male inherited genes

Inherit the genes on the X, but not on the Y, only have X, that trait is expressed wether it is dominant or recessive

Mutations

Any change in DNA (the order of the nucleotide bases/letters)

Mutagens

Chemicals that can cause DNA mutations, radiation, UV light, cigarette smoke

Beneficial mutation

A mutation accidentally makes it easier for an animal

Neutral mutation

A mutation causes a change which is neither harmful nor beneficial to survive

Harmful

A mutation that causes an unusual negative change

Gene mutation

A change that happens during DNA replication

Chromosome mutations

Happen during meiosis, changes the number or location of genes

Point mutations (gene mutation)

Substitute one nucleotide for another

Frameshift mutations (gene mutations)

The insertion or deletion of a nucleotide

Duplication (chromosome mutation)

Changes the size of chromosomes and results in multiple copies of the same gene