Bio Units 4/5 Study Cards

What are the stages of interphase?

G1- growing, S- duplicating DNA, G2- finishes growing, checks

What are the parts of cell division?

PMAT and cytokinesis

What happens in meiosis?

The creation of 4 unique haploid cells (sperm or egg), it is PMAT times 2

What happens in Meiosis 1

PMAT occurs, the homologous pairs separate, ends with 23 chromosomes and 46 chromatids, still a diploid

What happens in meiosis 2?

PMAT times 2, sister chromatids separate, ends with 4 haploid daughter cells (23 chromosomes and 23 chromatids)

PMAT 1

Prophase 1- chromosomes pair up, form tetrads, and cross over

Metaphase 1- pairs randomly line up in cell center, 23 chromosomes on each side

Anaphase 1- pairs separate to opposite ends, chromatids remain together, independent assortment occurs

Telophase 1- membrane reforms, creates two cells w/ unique combo of parents

Diagram

PMAT2

Prophase 2- membrane breaks down, spindle fibers assemble

Metaphase 2- spindle fibers align 23 chromosomes along equator

Anaphase 2- sister chromatids pulled apart/move to opposing sides

Telophase 2- membrane reforms, left with 4 unique haploid cells

Homologous chromosomes

A pair of chromosomes, one from each parent, code for same genes

Gametes

Sex cells

Haploid

a cell with one half genetic info

Diploid

A cell with full genetic info

How is genetic variation occurring?

Crossing over and independent assortment

Lactose

Sugar (disaccharide) found only in milk

Lactase

An enzyme that turns lactose into glucose and galactose

If you are lactose tolerant

Blood sugar spikes after drinking milk

Lactose tolerance is a

Selective advantage, which developed due to adaption to the consumption of milk

Genotype

The exact gene such as Gg or AA

Phenotype

the thing the gene codes for, such as Aa is brown hair

Homozygous

Homozygous dominant and recessive describe AA or aa

Heterozygous

Describes a gene such as Aa or Ss

Nondisjunction

When the homologous chromosomes fail to separate in anaphase of meiosis

Transcription

In the nucleus, DNA code turns into mRNA, uses RNA polymerase to separate the strands

Translation

In cytoplasm, at ribosomes, mRNA code is translated into amino acids, tRNA brings the correct amino acid to build the protein

Transcription and translation model

How do the letters in transcription and translation work?

During transcription, the original letters, A and T, which go together, and G and C, continue to the cytoplasm, but T turns into U

Central dogma

Flow of genetic info in cells- dna and rna

Nucleotide

4 types of nucleotides GCAT

mRNA

a vital type of RNA molecule that carries genetic instructions from DNA to the ribosomes, where proteins are synthesized

tRNA

a small RNA molecule that plays a crucial role in protein synthesis by acting as an adapter between messenger RNA (mRNA) and amino acids

rRNA

Ribosomal RNA (rRNA) is a key structural component of ribosomes, the organelles that synthesize proteins

Diagram different types of RNA

Codon

Sequence of 3 nucleotides

Point mutation

A change in a single base pair within a dna sequence (this includes insertion, substitution, deletion, etc)

Substitution mutation

One nucleotide base replaced with another

Insertion mutation

A nucleotide is added to the sequence, drastically changing it

Deletion mutation

A nucleotide is taken out of the sequence, changing it drastically

Silent mutation

When a mutation occurs in one mutation but doesn’t change the amino acid

Missense mutation

one nucleotide is replaced, causing a changed amino acid

Nonsense mutation

An early stop codon occurs

Frame shift mutation

One nucleotide is changed in the sequence, affecting the whole, and causing severe change to each amino acid

Melanin

Pigment produced in the skin, helps protect from UV radiation

Epidermis

Topmost layer of skin

Eumelanin

Black/brown form of melanin (found in larger amounts in darker skin)

Pheomelanin

Red/yellow form of melanin (found in larger amounts in lighter skin)

Melanocytes

Create melanin, which is packaged into melanosomes.

Melanosomes

Melanin is packaged into them by melanocytes, and they travel to keratinocytes and protect their nuclei

Vitamin D

UV rays help produce vitamin d, which is necessary for absorbing calcium

Folate

A chemical that is necessary in pregnant women to prevent birth defects. Without melanin protecting it, it will be broken down by UV.

Why did skin evolve over time?

To be balanced to protect folate and synthesize vitamin D based on levels of UV radiation in the area

Polygenic traits

Traits produced by two or more genes

5 Factors of Evolutionary change

Natural selection, mutation, gene flow, genetic drift, non-random mating (NMGGM)

Hardy Weinberg

Hypothetical, non-evolving population

Describes and measures how a population might change

P

Dominant allele frequency

Q

Recessive allele frequency

Equations

P + q = 1 (determines how many alleles)

P² + 2pq + q² = 1 (determines how many individuals)

Cancer and the cell cycle

Mutations in genes that regulate the cell cycle, such as oncogenes and tumor suppressor genes, can disrupt normal cell cycle control and contribute to cancer development

Telomerase

Cancer cells often activate telomerase, an enzyme that repairs the ends of chromosomes (telomeres), allowing them to continue dividing indefinitely

Checkpoints

The cell cycle is tightly regulated by checkpoints that monitor DNA damage, replication errors, and other factors. Cancer cells often lose control of these checkpoints, allowing them to divide even with damaged DNA or other abnormalities

Apoptosis

Apoptosis is the process of programmed cell death. It is used during early development to eliminate unwanted cells; for example, those between the fingers of a developing hand. In adults, apoptosis is used to rid the body of cells that have been damaged beyond repair. Apoptosis also plays a role in preventing cancer.

Contact inhibition

Contact inhibition is a process where cell growth and migration are halted due to contact with other cells

Hayflick limit

The Hayflick Limit is a biological concept that describes the limited number of times a normal human cell can divide before it enters a state of senescence, a process of cell aging and eventual death.

How do viruses infect/harm our cells?

They attach to the surface of the cell. Then, they insert their dna, which replaces the host dna. They then, through translation/transcription, copy this dna and create viral proteins. These proteins are finally released to begin to infect other cells.