Genetics - Biology unit 2

Meiosis

• produces gametes cells

• Haploids (23 chromosomes)

• Two-stage cell division

Mitosis

• produces body cells (stomatic cells)

• Diploids (46 chromosomes)

• One stage cell division

• Cells are identical to each other

Homologous chromosomes

Two separate chromosomes, that one from mother one from the father come together to form a pair are similar in shape size and hold the same type of genetic info.

Non-disjuction

homologous chromosomes fail to move to their opposite poles during meiosis resulting in gametes with too many or to few chromosomes

Gene

Specific part on the DNA strand the instruction certain characteristics of your body

Locus/loci

The specific location where a gene

Genotype

an individuals genetic makeup

3 types

Homozygous Dominant

Expressed with capital alleles

will always be expressed within the phenotype

Homozygous recessive

expressed with lowercase alleles

only expressed within the phenotype if theres no homo dom

Heterozygous

individual is a carrier of the genetic trait

Expressed with both capital and lowercase

Dominate masks the recessive

Phenotype

The physical makeup of genetic traits

Law of segregation

Each allele pair will separate when gametes is formed

Gametes can receive one pair or the other, never both

Law of independent assortment

• different pairs of alleles will not effect whoever get inherited

• can mix and match in four possible combinations

Autosomal Chromosomes

• The first 22 chromosomes

• same in both male and female

• karytypes are orders from largest chromsomes to smallest

• Bonding patterns are used to identifiy homologous chromosomes

Sex Chromosomes

• 23 chromsomes

• Females (XX)

• Males (XY)

• Y is always smaller

Who is mendal

The father of genetics

studied pea plants to understand inheritance patterns

Why did mendal use pea plant to study

because pea plant are easy to control mating, and fast growing, and you can tell when something has changed in them

Sister chromosomes

Identical copy of the same chromsome that are attached by a centromere

Spermatognesis

• forms sperm cells

• 4 useable gametes

Oogenesis

• forms egg cells

• 1 useable the rest die and give its nuitrents to the best egg

Complete dominance

when the dominate alleles mask the recessive alleles in a hetrozygous individual

Incomplete dominance

neither trait appears dominate and creates a blend instead

Co- dominance

clear display of both alleles

Monohybrid cross

2×2 cross to see the genotype of one trait

Dihybrid cross

4×4 cross to see the genotype of two traits

Sex linked traits

trait that can be found on the 23 chromosomes

Y- linked trait

trait that is aquired on the y chromosome on males can have this

Autosomal inheritance

the way genetic traits are passed down in the first 22 chromosomes

DNA

• Deoxyribonucleic acid

• stores genetic info

Nucleotide

Basic units that are linked together to make up a DNA strand (3 parts)

Spontaneous mutation

• not due to outside factors

• random meisois/mitosis mistake

Induced mutation

mutation caused by exposure to outside factors

Human Genome

Sequence of all human DNA on 23 chromosomes

What occurs during mitosis

1. interphase - cell spend 90% time here

2. Prophase - chromatin condense into chromosomes and nuclear mebrane dissolves allowing centroiles move to the opposite side forming splindle fibers

3. Metaphase chromsomes begin to line down the middle and splindle fiber attatches itself on the chromosomes

4. Anaphase - sister chromatids are now being pulled apart onto their pole

5. Telophase - nuclear membrane dissolves and cytoplasm pinches down the middle forming two new cells

Whats the beginning and ending chromosome count in mitosis

46

Whats the haploid number

23

whats the diploid number

46

when are haploids created

through gametes cells

when are diploids created

through mitosis

Why are haploids created in meiosis

because each gamete cell has to have one half of the parents DNA (23 chromsomes) so that when they come together it will be a total of 46 which means its human

Explain the stages of Meiosis

Prophase 1 - chromotids begin to condense turning into chromosomes, nuclear membrane dissolves homolougous chromsomes pair up and cross over during synapsis to exchange genetic material, centrioles move to their pole

Metaphase 1 - chromosomes line down the middle in thair and microtubules pull on each pair

Anaphase 1 - homlogous chromsomes are seperated and pulled to their pole

Telopahse 1 - chromsomes reach pole new nuclear membrane froms and cytoplasm pinches inwards creating two cells

Prophase 2 - nuclear membrane dissolves centrioles move to pole

Metaphase 2 chromsomes line up and microtubles attach to the chromosome

Anaphase 2 - chromsomes are pulled apart into chromatids

Telophase 2 - chromatide uncoil and nuclear membrane froms

Cytokinesis - cytoplasm punches froming 2 new cells now there is four cells with 23 chromsomes each

Compare and contrast mitoisis and meiosis

Compare - both create cells, both go through PMAT once

Contrast - meiosis is a haploid, mitosis is diploid

Synapsis

The physical process of chromosomes pairing up

Crossing over

Exchanging genetic into

Why is crossing over important

Because it increases genetic variety

Why is red/green color blindness more common in human males than females?

red green colour blindness is on the x chromosome males only have one x chromsome so if that x chromsome has it then they def will get it, while females have two x chromosomes so they could possibly avoid it

What is a pedigree chart used for?

Used to visual a family tree and track down specific traits/diesases

What are the symbols on a pedigree chart

square = men

circle = women

Affected = fully shaded

Carrier = half shaded

how to tell if a trait on the pedigree is recessive or dominant

Dominate - every affected person has one affected parent

Autosomal dominate - homozygous recessive

Recessive traits can skip gens, and are homozygous recessive

Karyotypes

an individuals complete set of chromosomes

How are karyotypes made

by collecting a tissue sample and encouraging cells to divide

What are the disorders found in karyotypes

Translocation - extra chunk on one chromosome

Monosomy - missing chromosome

Trisomy - extra chromosome

What is a carrier

a person who carriers the genetic dieases but is not affected by it because their dominate genes take over

Explain how a couple could have a child with cystic fibrosis, but no one in either of their families has had the disease to their knowledge.

If both parents are carriers, then the gene that is recessive can be passed down to the kid with no dominate gene to overrule

Describe the structure of DNA (3 components

1. Sugar: Deoxyribose, a five-carbon sugar molecule that forms the backbone of DNA.

Phosphate Group: A phosphate group linked to the sugar, contributing to the DNA backbone

Nitrogenous Bases: Four types (adenine, thymine, cytosine, and guanine) that pair specifically (A with T and C with G), encoding genetic information.

What are the 4 nucleotides that make up DNA

Adenine (A) 2. Thymine (T) 3. Cytosine (C) 4. Guanine (G)

Complementary base pairing

A with T, C with G

What is a mutation?

a permanent random change in the DNA sequence

Point mutation: substitution

when a single nucleotide is replaced by another

Point mutation: insertion

when a nucleotide is added

Point mutation: duplication

when another of the same nucleotide is added

Transpoons

Genes that can move from one section of the genome to another

Coding DNA

Contains genes that give instructions to make  proteins/phenotypes

Coding DNA

Inactive DNA which is the majority of the genome, doesn't order stuff to be made

Genetic engineering

putting gene from one organism into another that doesn have those genes or it doesnt work properly

Restriction enzymes + example

“chemical scissors” that cut out specific DNA sequences from an organism Spider Silk: Web spinning gene put into goats to make strong silk from milk

Gene Therapy setbacks + successes

Branch of genetic engineering where modified virus cells are used to replace the genome

Setbacks: Hard to control, viral DNA can reactivate and damage cells, immune system may attack viral cell

Successes: Dog vision restoration, guinea pig hearing restoration