SBI3UP - Genetics

lesson 1 : genetics intro

chromosomes (animals)

structures inside the nucleus of eukaryotic cells that carry genetic info for traits

genetic info is found in

DNA

Different species differ (how do their chromosomes differ)

in their number, shape, & size.

heredity

the passing of traits from parent to offspring

Genetics

branch of biology dealing with heredity and the variation of inherited characteristics

genetic info hierarchy

cell >nucleus>chromosome>dna

genetic material

all material in an organism that stores genetic information

A typical human chromosome contains ______ of ____.

thousands, genes

eukaryotic

Cells with a nucleus and membrane bound organelles

prokaryotes

with no membrane bound organelles or nucleus

chromosomes are made of

DNA and proteins

gene

segment of a dna molecule that codes for a particular trait found at a specific location on a chromosome

locus

location of gene on a chromosome

genes are

strategically organized

a typical human chromosome contains

thousands of genes

each gene is located at a different ___

locus

gene purpose

acts as instructions

humans have chromosomes in __

sets

diploid cells

have two sets of chromosomes (2n)

haploid cells

(n) cells have half the normal number of chromosomes e..g. sperms and eggs

it starts at ___ and gets half as you go

diploid

polyploids

(3n or more) 3 or more sets of chromosomes e.g. strawbery octoploid

these two organelles also contain small amounts of genetic material

mitochondria

chloroplasts

generally all genetic material is found in the

nucleus

humans have how many pairs of chromosomes, how many individual

23, 46

two types of reproduction

sexual

asexual

sexual

2 parents (meiosis)

asexual

1 parent (mitosis)

describe asexual reproduction

-new individual produced by cell division: mitosis

-chromosomes of parent is duplicated and divided

-no genetic diversity

-daughter cells genetically identical to parent

advantages of asexual reproduction

- no need to find a partner ; less energy required or time wasted

- no specialized anatomy required

- direct reproduction - heredities is invariable and generations of offspring are (usually) identical to parents unless mutations

- no need for mating behaviours

disadvantages of asexual reproduction

- difficult adapting to environment (volcano, climate change, evolution)

- little genetic diversity

-individuals equally susceptible to: many diseases, killing all organisms easily

-losing competition for resources with other species (all eat the same, use same resources, fast depletion and fierce competition)

sexual reproduction description

- production of offspring from the fusion of two sex cells (two different parents USUALLY)

-offsprings are genetically different from their parents and from each other

-obtain half the genetic info from each parents

- offspring are genetically variable

disadvantages of sexual reproduction

-you need to find/attract a mate (more energy and time required)

-mating calls and bright-coloured for attraction: this attracts predators as well as mates (e.g. male peacock)

-special anatomy

-plants need pollinators, nectar to attract them

- new gene combination may not be advantageous

(weak and unable to survive)

advantages of sexual reproduction

- genetic diversity/variability protects against: disease and environmental changes

-adapt easily

-less competition with other species for resources

sexual organisms vs asexual

-sexual more complex (bigger) vs asexual less complex (smaller)

-more complex systems or parts vs not

-2 parents vs 1 parent

-sexual reproduction vs binary fission (amoeba, bacteria), budding, fragmentation

- more parental care or first meal and parent leaves vs almost to none

- many offspring vs less

-more genetic variation vs none genetic variation (unless mutation)

asexual repro. has no genetic variation unless _____ happens

mutation

______ and _______ are biological processes that are fundamental to life.

CELL DIVISION

REPRODUCTION

Multicellular organisms use cell division for

growth and repair

unicellular organisms use it as a means of

reproduction

A key feature of cell division and reproduction is

the passing of chromosomes from the parent cell to the daughter cells

mostly plants have ____

polyploids

multicellular organisms usually have ___

diploids

What is the relationship between chromosomes, DNA, and a gene?

chromosomes contain genetic material/information through molecules of DNA and have protein

DNA contain segments of genetic sequences found on loci of the chromosome called genes which contain the information of traits to pass down

Brainstorm examples of environmental changes that are: (i) sudden and rapid, (ii) slow and gradual.

i) flash flood, flash drought

ii) mountain formation, rising temperatures, rising sea levels

a chromosome can be single or ___

half two sections (still counted as 1)

sexual reproduction steps

1. egg (woman) + sperm (man)

2. zygote fertilization

3.embryo

sex cells

male = sperm cell

female = egg cell

each sex cell has ___ chromosomes

23

zygote and embryo has ___ chromosomes and _ pairs in total

46, 23

l2: asexual reproduction

Many organisms reproduce ______ for at least ____ of their _________

asexually

part

life cycle

Most common among which groups

unicellular organisms, but also widespread among multicellular groups (plants and fungi)

some organisms are ____ first but then ___ later

asexual

sexual

types of asexual reproduction

pulling out roots or shoots

budding

fragmentation

pulling out roots or shoots

Above ground stems extend / develop into new plants (strawberry)

Budding

New individual develops from an outgrowth on the body of an organism (hydra, jellyfish)

Fragmentation

Parts of the growing mass break off and continue to grow independently (fungi)

Aphids

females give birth to female offspring

offspring can give birth to more females at only a few days old

numbers/population can skyrocket in a few weeks!

hormonal changes occur in autumn and they start giving birth to males

now sexual reproduction is possible and genetic diversity

cell cycle (3 main stages)

interphase, mitosis, cytokinesis

interphase

when the genetic material (in the form of chromatin) is duplicated

mitosis

genetic material in the nucleus is divided equally into new NUCLEI (NOT CELLS)

cytokinesis

when the rest of the cell actually divides into two daughter cells

stages of mitosis

prophase

metaphase

anaphase

telophase

chromatin

tangled strands of dna & protein within eukaryotic nucleus

sister chromatid

identical copy of a single chromosome that remains attached to the original chromosome at the centromere

duplicated chromosome that has its original and duplicated attached together

a single chromosome and a sister chromatid is still ___ chromosome

one

chromosome is

condensed chromatin

unreplicated chromosome

chromatid

centromere

where things are attached to the chromosome, middle

interphase

-longest phase

interphase divided into several parts

G1 ap

S ynthesis

G2 ap

Dna is in the form of

chromatin

G1

cellular contents not chromosomes are duplicated

S

duplicated chromosomes

G2

checks for mutations or errors, can correct, seeks errors in duplicated chromosomes, repairs

mitosis: prophase

chromatin condenses & becomes visible (now called sister chromatids/duplicated chromosomes)

nuclear membrane begins to dissolve

centrioles move to opposite ends of cell

spindle fibres form from centrioles

centromere helps anchor the chromosomes to spindle fibre

nucleolus disappears

why does nuclear membrane dissolve

you do not need dna to stay in one place. you need it to move around

metaphase

spindle fibers attach to the chromosomes at the centromere, begin moving and aligning

duplicated chromosomes are pulled towards the centre of the cell

centromeres line up at the equator of cell

anaphase

centromere splits into two and the sister chromatids separate (now referred as chromosomes)

spindle fibers pull sister chromatids to opposite poles of the cell

chromosomes pulled by their centromeres

if mitosis is correct, same number and type of chromosomes will be found at each pole of the cell

telophase

chromosomes reach the opposite poles of the cell and begin to unwind

spindle fibres dissolve

nuclear membranes form around chromosomes

nucleolus reforming

results in 2 daughter NUCLEIIII

cytokinesis (not mitosis)

cytoplasm and organelles separate roughly into equal parts

2 identical daughter cells are formed

TWO NEW CELLS. not nuclei

Animal cells undergo cytokinesis through the formation of a _____ ___

cleavage furrow

cleavage furrow formation

A ring of microfilaments contract, pinching the cell in half.

Plant cells undergo cytokinesis by forming a _____ _____ between the two daughter nuclei.

cell plate

cell plate formation

Cell plate forms by vesicles that gather together and fuse.

outcome of cell cycle

Two daughter cells each containing identical genetic information

Daughter cells - same number of chromosomes as the parent

For growth and repair in multicellular

MITOSIS DAUGHTER CELLS HAVE THE ____ amount of chromosomes as parent

SAME/EQUAL

mitosis acronym

PMAT

cells divide at a ____ rate

different

examples of cells that divide fast

skin

stomach

cells that do not divide at all

muscle

nerve

Cloning

Producing a genetically- identical

copy of a living organism using a single cell or tissue

cloning disadvantages

detrimental traits: more susceptible to diseases and illnesses

can be expensive and time consuming

consumer dissatisfaction and ethics

loss of genetic diversity

cloning advantages

cloning for desired traits

repopulate endangered species

mass production of plants and animals

commercial

applications of cloning (GOOD)

Cloning genetically modified organisms (GMOs)

example

genetically modify a plant to produce insulin

human clones

Clones for organ harvesting

Soldiers, athletes, drone workers, etc.

issues with human clones

moral

ethical

Health concerns

plant cloning steps

1. individual cells extracted from parent

2. individual cells begin dividing and growing

3. cells specialize and produce clone